diff --git a/pkNX.Containers/Container.cs b/pkNX.Containers/Container.cs
index c24ee910..559b00f3 100644
--- a/pkNX.Containers/Container.cs
+++ b/pkNX.Containers/Container.cs
@@ -28,7 +28,7 @@ public static IFileContainer GetContainer(string path, ContainerType t)
         /// Gets a <see cref="IFileContainer"/> for the stream.
         /// </summary>
         /// <param name="path">Path to the binary data</param>
-        public static IFileContainer GetContainer(string path)
+        public static IFileContainer? GetContainer(string path)
         {
             var fs = new FileStream(path, FileMode.Open);
             var container = GetContainer(fs);
@@ -45,7 +45,7 @@ public static IFileContainer GetContainer(string path)
         /// Gets a <see cref="IFileContainer"/> for the stream.
         /// </summary>
         /// <param name="stream">Stream for the binary data</param>
-        public static IFileContainer GetContainer(Stream stream)
+        public static IFileContainer? GetContainer(Stream stream)
         {
             var br = new BinaryReader(stream);
             var container = GetContainer(br);
@@ -58,9 +58,9 @@ public static IFileContainer GetContainer(Stream stream)
         /// Gets a <see cref="IFileContainer"/> for the stream within the <see cref="BinaryReader"/>.
         /// </summary>
         /// <param name="br">Reader for the binary data</param>
-        public static IFileContainer GetContainer(BinaryReader br)
+        public static IFileContainer? GetContainer(BinaryReader br)
         {
-            IFileContainer container;
+            IFileContainer? container;
             if ((container = GARC.GetGARC(br)) != null)
                 return container;
             if ((container = MiniUtil.GetMini(br)) != null)
diff --git a/pkNX.Containers/ContainerHandler/ContainerHandler.cs b/pkNX.Containers/ContainerHandler/ContainerHandler.cs
index c2069ace..7a69ff3e 100644
--- a/pkNX.Containers/ContainerHandler/ContainerHandler.cs
+++ b/pkNX.Containers/ContainerHandler/ContainerHandler.cs
@@ -6,8 +6,8 @@ namespace pkNX.Containers
 {
     public sealed class ContainerHandler
     {
-        public event EventHandler<FileCountDeterminedEventArgs> FileCountDetermined;
-        public event EventHandler<FileProgressedEventArgs> FileProgressed;
+        public event EventHandler<FileCountDeterminedEventArgs>? FileCountDetermined;
+        public event EventHandler<FileProgressedEventArgs>? FileProgressed;
 
         private int count;
 
@@ -18,11 +18,11 @@ public void Initialize(int total)
             FileCountDetermined?.Invoke(null, args);
         }
 
-        public void StepFile(int ctr, int total = -1, string fileName = null)
+        public void StepFile(int ctr, int total = -1, string? fileName = null)
         {
             if (total < 0)
                 total = count;
-            var args = new FileProgressedEventArgs {Current = ctr, Total = total, CurrentFile = fileName};
+            var args = new FileProgressedEventArgs {Current = ctr, Total = total, CurrentFile = fileName ?? string.Empty};
             FileProgressed?.Invoke(null, args);
         }
     }
diff --git a/pkNX.Containers/ContainerHandler/FileProgressedEventArgs.cs b/pkNX.Containers/ContainerHandler/FileProgressedEventArgs.cs
index 7b49e7bd..2a7a2aba 100644
--- a/pkNX.Containers/ContainerHandler/FileProgressedEventArgs.cs
+++ b/pkNX.Containers/ContainerHandler/FileProgressedEventArgs.cs
@@ -6,6 +6,6 @@ public class FileProgressedEventArgs : EventArgs
     {
         public int Current { get; set; }
         public int Total { get; set; }
-        public string CurrentFile { get; set; }
+        public string? CurrentFile { get; set; }
     }
 }
\ No newline at end of file
diff --git a/pkNX.Containers/FakeContainer.cs b/pkNX.Containers/FakeContainer.cs
index bbf3bb74..6d20bf20 100644
--- a/pkNX.Containers/FakeContainer.cs
+++ b/pkNX.Containers/FakeContainer.cs
@@ -17,7 +17,7 @@ public FakeContainer(byte[][] files)
                 Backup[i] = (byte[])files[i].Clone();
         }
 
-        public string FilePath { get; set; } = string.Empty;
+        public string? FilePath { get; set; } = string.Empty;
         public bool Modified { get; set; }
         public int Count => Files.Length;
 
diff --git a/pkNX.Containers/FileMitm.cs b/pkNX.Containers/FileMitm.cs
index 07703add..dd62a41e 100644
--- a/pkNX.Containers/FileMitm.cs
+++ b/pkNX.Containers/FileMitm.cs
@@ -12,8 +12,8 @@ public static class FileMitm
         public static void EnableIfSetup() => Enabled = PathOriginal != null;
         public static void Disable() => Enabled = false;
 
-        private static string PathOriginal;
-        private static string PathRedirect;
+        private static string? PathOriginal;
+        private static string? PathRedirect;
 
         public static byte[] ReadAllBytes(string path)
         {
@@ -23,6 +23,8 @@ public static byte[] ReadAllBytes(string path)
 
         public static void WriteAllBytes(string path, byte[] data)
         {
+            if (string.IsNullOrWhiteSpace(path))
+                throw new FileNotFoundException("Invalid filename.");
             path = GetRedirectedWritePath(path);
             File.WriteAllBytes(path, data);
         }
diff --git a/pkNX.Containers/FolderContainer.cs b/pkNX.Containers/FolderContainer.cs
index 4a45b596..1c969357 100644
--- a/pkNX.Containers/FolderContainer.cs
+++ b/pkNX.Containers/FolderContainer.cs
@@ -10,16 +10,18 @@ namespace pkNX.Containers
     public class FolderContainer : IFileContainer
     {
         private readonly List<string> Paths = new();
-        private readonly List<byte[]> Data = new();
+        private readonly List<byte[]?> Data = new();
         private readonly List<bool> TrackModify = new();
 
+        public string? FilePath { get; set; }
+
         public FolderContainer() { }
         public FolderContainer(IEnumerable<string> files) => AddFiles(files);
 
         public FolderContainer(string path) => FilePath = path;
         public FolderContainer(string path, Func<string, bool> filter) : this(path) => Initialize(filter);
 
-        public void Initialize(Func<string, bool> filter = null)
+        public void Initialize(Func<string, bool>? filter = null)
         {
             if (Paths.Count > 0)
                 return; // already initialized
@@ -30,7 +32,7 @@ public void Initialize(Func<string, bool> filter = null)
             AddFiles(files);
         }
 
-        public void AddFile(string file, byte[] data = null)
+        public void AddFile(string file, byte[]? data = null)
         {
             Paths.Add(file);
             Data.Add(data);
@@ -43,7 +45,7 @@ public void AddFiles(IEnumerable<string> files)
                 AddFile(f);
         }
 
-        public byte[] GetFileData(string file)
+        public byte[]? GetFileData(string file)
         {
             var index = Paths.FindIndex(z => Path.GetFileName(z) == file);
             if (index < 0)
@@ -55,8 +57,6 @@ public byte[] GetFileData(string file)
 
         public byte[] GetFileData(int index)
         {
-            if (index < 0 || (uint)index >= Data.Count)
-                return null;
             var data = Data[index] ??= FileMitm.ReadAllBytes(Paths[index]);
             return (byte[])data.Clone();
         }
@@ -66,18 +66,20 @@ public byte[] GetFileData(int index)
             get => GetFileData(index);
             set
             {
-                if (value != null)
-                {
-                    var current = Data[index] ??= GetFileData(index);
-                    TrackModify[index] = !value.SequenceEqual(current);
-                }
+                var current = Data[index] ??= GetFileData(index);
+                TrackModify[index] = !value.SequenceEqual(current);
+
                 Data[index] = value;
             }
         }
 
-        public string GetFileName(int index) => Paths[index];
+        public void ResetIndex(int index)
+        {
+            Data[index] = null;
+            TrackModify[index] = false;
+        }
 
-        public string FilePath { get; set; }
+        public string GetFileName(int index) => Paths[index];
 
         public bool Modified
         {
diff --git a/pkNX.Containers/GARC/FATBEntry.cs b/pkNX.Containers/GARC/FATBEntry.cs
index 906b4888..06068fb9 100644
--- a/pkNX.Containers/GARC/FATBEntry.cs
+++ b/pkNX.Containers/GARC/FATBEntry.cs
@@ -10,15 +10,14 @@ internal class FATBEntry
         public readonly bool IsFolder;
         public readonly FATBSubEntry[] SubEntries;
 
-        // ReSharper disable once UnusedMember.Local -- needed to init subentries
         private FATBEntry()
         {
-            SubEntries = new FATBSubEntry[32];
-            for (int i = 0; i < SubEntries.Length; i++)
-                SubEntries[i] = new FATBSubEntry();
+            var sub = SubEntries = new FATBSubEntry[32];
+            for (int i = 0; i < sub.Length; i++)
+                sub[i] = new FATBSubEntry();
         }
 
-        public FATBEntry(string file)
+        public FATBEntry(string file) : this()
         {
             IsFolder = false;
             Vector = 1;
@@ -26,7 +25,7 @@ public FATBEntry(string file)
             SubEntries[0].File = file;
         }
 
-        public FATBEntry(IEnumerable<string> files)
+        public FATBEntry(IEnumerable<string> files) : this()
         {
             IsFolder = true;
             Vector = 0;
@@ -45,7 +44,7 @@ public FATBEntry(IEnumerable<string> files)
             }
         }
 
-        public FATBEntry(BinaryReader br, int DataOffset)
+        public FATBEntry(BinaryReader br, int DataOffset) : this()
         {
             Vector = br.ReadUInt32();
 
diff --git a/pkNX.Containers/GARC/FATO.cs b/pkNX.Containers/GARC/FATO.cs
index 4900fdda..9b166b84 100644
--- a/pkNX.Containers/GARC/FATO.cs
+++ b/pkNX.Containers/GARC/FATO.cs
@@ -8,7 +8,7 @@ internal class FATO
 
         private readonly uint Magic = MAGIC;
         private readonly int HeaderSize = 0xC;
-        private readonly ushort EntryCount;
+        public readonly ushort EntryCount;
         private readonly short Padding = -1;
 
         private FATOEntry[] Entries { get; }
diff --git a/pkNX.Containers/GARC/GARC.cs b/pkNX.Containers/GARC/GARC.cs
index 0f601650..51337736 100644
--- a/pkNX.Containers/GARC/GARC.cs
+++ b/pkNX.Containers/GARC/GARC.cs
@@ -12,22 +12,26 @@ public class GARC : LargeContainer
         private FATO FATO;
         private FATB FATB;
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
         public GARC(BinaryReader br) => OpenRead(br);
         public GARC(string file) => OpenBinary(file);
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 
         public GARC(IReadOnlyList<string> files, GARCVersion version = GARCVersion.VER_6)
         {
             Header = new GARCHeader(version);
             FATO = new FATO(files.Count);
             FATB = new FATB(files);
+            Files = new byte[]?[files.Count];
         }
 
         protected override void Initialize()
         {
-            Reader.BaseStream.Position = 0;
+            Reader!.BaseStream.Position = 0;
             Header = new GARCHeader(Reader);
             FATO = new FATO(Reader);
             FATB = new FATB(Reader, Header.DataOffset);
+            Files = new byte[]?[FATO.EntryCount];
         }
 
         protected override int GetFileOffset(int file, int subFile = 0)
@@ -42,12 +46,12 @@ public override byte[] GetEntry(int index, int subFile)
             if (f.File is byte[] data)
                 return data;
 
-            data = f.GetFileData(Reader.BaseStream);
+            data = f.GetFileData(Reader!.BaseStream);
             f.File = data; // cache for future fetches
             return data;
         }
 
-        public override void SetEntry(int index, byte[] value, int subFile)
+        public override void SetEntry(int index, byte[]? value, int subFile)
         {
             Modified |= value != null && !GetEntry(index, subFile).SequenceEqual(value);
             var f = FATB[index].SubEntries[subFile];
@@ -94,7 +98,7 @@ private void WriteIntro(BinaryWriter bw, bool lastPass = false)
         private void WriteEntry(BinaryWriter bw, int i, int DataOffset)
         {
             FATO[i].Offset = (uint)bw.BaseStream.Position;
-            FATB[i].WriteEntries(bw, Reader?.BaseStream, Header.ContentPadToNearest, DataOffset,
+            FATB[i].WriteEntries(bw, Reader!.BaseStream, Header.ContentPadToNearest, DataOffset,
                 ref Header.ContentLargestUnpadded, ref Header.ContentLargestPadded);
         }
 
@@ -108,12 +112,12 @@ public override void Dump(string path, ContainerHandler handler)
             handler.Initialize(Count);
             for (int i = 0; i < Count; i++)
             {
-                FATB[i].Dump(path, i, format, Reader.BaseStream, Header.DataOffset);
+                FATB[i].Dump(path, i, format, Reader!.BaseStream, Header.DataOffset);
                 handler.StepFile(i+1);
             }
         }
 
-        public static GARC GetGARC(BinaryReader br)
+        public static GARC? GetGARC(BinaryReader br)
         {
             if (br.BaseStream.Length < 20)
                 return null;
diff --git a/pkNX.Containers/IFileContainer.cs b/pkNX.Containers/IFileContainer.cs
index 77da7bd6..65ed294c 100644
--- a/pkNX.Containers/IFileContainer.cs
+++ b/pkNX.Containers/IFileContainer.cs
@@ -12,7 +12,7 @@ public interface IFileContainer
         /// <summary>
         /// Path the <see cref="IFileContainer"/> was loaded from.
         /// </summary>
-        string FilePath { get; set; }
+        string? FilePath { get; set; }
 
         /// <summary>
         /// Indication if the contents of the <see cref="IFileContainer"/> have been modified.
diff --git a/pkNX.Containers/LargeContainer.cs b/pkNX.Containers/LargeContainer.cs
index 906e3099..45549c9a 100644
--- a/pkNX.Containers/LargeContainer.cs
+++ b/pkNX.Containers/LargeContainer.cs
@@ -14,16 +14,16 @@ public abstract class LargeContainer : IDisposable, IFileContainer
     {
         public virtual int Count => Files.Length;
 
-        public Task<byte[][]> GetFiles() => new(() => { CacheAll(); return Files; });
+        public Task<byte[][]> GetFiles() => new(() => { CacheAll(); return Files!; });
         public Task<byte[]> GetFile(int file, int subFile = 0) => new(() => GetEntry(file, subFile));
         public Task SetFile(int file, byte[] value, int subFile = 0) => new(() => SetEntry(file, value, subFile));
 
-        public string Extension => Path.GetExtension(FilePath);
-        public string FileName => Path.GetFileName(FilePath);
-        public string FilePath { get; set; }
+        public string? Extension => Path.GetExtension(FilePath);
+        public string? FileName => Path.GetFileName(FilePath);
+        public string? FilePath { get; set; }
         public bool Modified { get; set; }
 
-        protected byte[][] Files { get; set; }
+        protected byte[]?[] Files = Array.Empty<byte[]>();
 
         /// <summary>
         /// Packs the <see cref="LargeContainer"/> to the specified writing stream.
@@ -36,8 +36,8 @@ public abstract class LargeContainer : IDisposable, IFileContainer
 
         #region File Reading
 
-        protected BinaryReader Reader { get; private set; }
-        private Stream Stream;
+        protected BinaryReader? Reader { get; private set; }
+        private Stream? Stream;
 
         protected void OpenBinary(string path)
         {
@@ -60,6 +60,8 @@ protected void OpenRead(BinaryReader br)
 
         public BinaryReader Seek(int file, long offset = 0, int subFile = 0)
         {
+            if (Reader == null)
+                throw new NullReferenceException("Reader is not initialized.");
             offset += GetFileOffset(file, subFile);
             Reader.BaseStream.Position = offset;
             return Reader;
@@ -67,7 +69,7 @@ public BinaryReader Seek(int file, long offset = 0, int subFile = 0)
 
         public abstract byte[] GetEntry(int index, int subFile);
 
-        public virtual void SetEntry(int index, byte[] value, int subFile)
+        public virtual void SetEntry(int index, byte[]? value, int subFile)
         {
             Files[index] = value;
             Modified |= value != null && !this[index].SequenceEqual(value);
@@ -92,7 +94,8 @@ public void CacheAll()
                 Files[i] ??= GetCachedValue(i, 0);
 
             Reader = null;
-            Stream.Close();
+            Stream?.Close();
+            Stream = null;
         }
 
         public void CancelEdits()
@@ -143,8 +146,8 @@ public void Dispose()
 
         protected virtual void Dispose(bool disposing)
         {
-            Stream.Dispose();
-            Reader.Dispose();
+            Stream?.Dispose();
+            Reader?.Dispose();
         }
     }
 }
diff --git a/pkNX.Containers/LargeContainerEntry.cs b/pkNX.Containers/LargeContainerEntry.cs
index 30ae6a97..aa9a7624 100644
--- a/pkNX.Containers/LargeContainerEntry.cs
+++ b/pkNX.Containers/LargeContainerEntry.cs
@@ -7,7 +7,7 @@ public class LargeContainerEntry
         public int Start { get; set; }
         public int End { get; set; }
         public virtual int Length { get; set; }
-        public object File { get; set; }
+        public object? File { get; set; }
         public int ParentDataPosition { get; set; }
 
         public byte[] GetFileData(Stream parent)
diff --git a/pkNX.Containers/Mini/Mini.cs b/pkNX.Containers/Mini/Mini.cs
index 1c2777d2..e8552a7e 100644
--- a/pkNX.Containers/Mini/Mini.cs
+++ b/pkNX.Containers/Mini/Mini.cs
@@ -29,7 +29,7 @@ public Mini(byte[][] data, string ident)
             }
         }
 
-        public string FilePath { get; set; }
+        public string? FilePath { get; set; }
         private readonly byte[][] Backup;
 
         public bool Modified { get; set; }
diff --git a/pkNX.Containers/Mini/MiniUtil.cs b/pkNX.Containers/Mini/MiniUtil.cs
index 69ab3499..c22cb3f1 100644
--- a/pkNX.Containers/Mini/MiniUtil.cs
+++ b/pkNX.Containers/Mini/MiniUtil.cs
@@ -30,10 +30,10 @@ public static byte[] PackMini(byte[][] fileData, string identifier)
             int dataOffset = 4 + 4 + (count * 4);
 
             // Start the data filling.
-            using MemoryStream dataout = new MemoryStream();
-            using MemoryStream offsetMap = new MemoryStream();
-            using BinaryWriter bd = new BinaryWriter(dataout);
-            using BinaryWriter bo = new BinaryWriter(offsetMap);
+            using MemoryStream dataout = new();
+            using MemoryStream offsetMap = new();
+            using BinaryWriter bd = new(dataout);
+            using BinaryWriter bo = new(offsetMap);
             // For each file...
             for (int i = 0; i < count; i++)
             {
@@ -60,21 +60,21 @@ public static byte[] PackMini(byte[][] fileData, string identifier)
             return newPack.ToArray();
         }
 
-        public static byte[][] UnpackMini(string file, string identifier = null)
+        public static byte[][] UnpackMini(string file, string identifier)
         {
             byte[] fileData = FileMitm.ReadAllBytes(file);
             return UnpackMini(fileData, identifier);
         }
 
-        public static byte[][] UnpackMini(byte[] fileData, string identifier = null)
+        public static byte[][] UnpackMini(byte[] fileData, string identifier)
         {
-            if (fileData == null || fileData.Length < 4)
-                return null;
+            if (fileData.Length < 4)
+                throw new ArgumentOutOfRangeException(nameof(fileData));
 
-            if (identifier?.Length == 2)
+            if (identifier.Length == 2)
             {
                 if (identifier[0] != fileData[0] || identifier[1] != fileData[1])
-                    return null;
+                    throw new FormatException("Prefix does not match.");
             }
 
             int count = BitConverter.ToUInt16(fileData, 2); int ctr = 4;
@@ -97,10 +97,13 @@ public static Mini GetMini(string path)
             path = FileMitm.GetRedirectedReadPath(path);
             using var fs = new FileStream(path, FileMode.Open, FileAccess.Read);
             using var br = new BinaryReader(fs);
-            return GetMini(br);
+            var result = GetMini(br);
+            if (result is null)
+                throw new FormatException($"The file at {path} is not a {nameof(Mini)} file.");
+            return result;
         }
 
-        public static Mini GetMini(BinaryReader br)
+        public static Mini? GetMini(BinaryReader br)
         {
             var ident = GetIsMini(br);
             if (string.IsNullOrEmpty(ident))
@@ -115,18 +118,18 @@ public static Mini GetMini(BinaryReader br)
         public static string GetIsMini(BinaryReader br)
         {
             if (br.BaseStream.Length < 12)
-                return null;
+                return string.Empty;
             br.BaseStream.Position = 0;
             var ident = br.ReadBytes(2);
             var count = br.ReadUInt16();
 
             int finalLengthOfs = 4 + (count * 4);
             if (br.BaseStream.Length < finalLengthOfs + 4)
-                return null;
+                return string.Empty;
             br.BaseStream.Position = 4 + (count * 4);
             var len = br.ReadUInt32();
             if (len != br.BaseStream.Length)
-                return null;
+                return string.Empty;
             return $"{(char)ident[0]}{(char)ident[1]}";
         }
 
diff --git a/pkNX.Containers/Misc/BinaryRWExtensions.cs b/pkNX.Containers/Misc/BinaryRWExtensions.cs
index 0bd2290b..3f69d733 100644
--- a/pkNX.Containers/Misc/BinaryRWExtensions.cs
+++ b/pkNX.Containers/Misc/BinaryRWExtensions.cs
@@ -35,7 +35,7 @@ public static string ReadNXString(this BinaryReader br)
 
         public static string ReadStringBytesUntil(this BinaryReader br, byte end = 0)
         {
-            StringBuilder str = new StringBuilder();
+            StringBuilder str = new();
             byte b;
             while ((b = br.ReadByte()) != end)
                 str.Append((char)b);
diff --git a/pkNX.Containers/Misc/GFPack.cs b/pkNX.Containers/Misc/GFPack.cs
index b1fc1688..d99bdff9 100644
--- a/pkNX.Containers/Misc/GFPack.cs
+++ b/pkNX.Containers/Misc/GFPack.cs
@@ -24,6 +24,7 @@ public class GFPack : IEnumerable<byte[]>, IFileContainer
         public byte[][] CompressedFiles { get; set; }
         public byte[][] DecompressedFiles { get; set; }
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
         public GFPack(string path) : this(FileMitm.ReadAllBytes(path)) => FilePath = path;
         public GFPack(string[] directories, string parent = @"\bin") => LoadFiles(directories, parent);
 
@@ -39,6 +40,7 @@ public GFPack(byte[] data)
         }
 
         public GFPack(BinaryReader br) => ReadPack(br);
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 
         private void ReadPack(BinaryReader br)
         {
@@ -212,8 +214,7 @@ private static byte[] Decompress(byte[] encryptedData, int decryptedLength, Comp
             return type switch
             {
                 CompressionType.None => encryptedData,
-                CompressionType.Zlib => null // not implemented
-                ,
+                CompressionType.Zlib => throw new NotSupportedException(nameof(CompressionType.Zlib)), // not implemented
                 _ => LZ4.Decode(encryptedData, decryptedLength)
             };
         }
@@ -223,8 +224,7 @@ private static byte[] Compress(byte[] decryptedData, CompressionType type)
             return type switch
             {
                 CompressionType.None => decryptedData,
-                CompressionType.Zlib => null // not implemented
-                ,
+                CompressionType.Zlib => throw new NotSupportedException(nameof(CompressionType.Zlib)), // not implemented
                 _ => LZ4.Encode(decryptedData)
             };
         }
@@ -260,7 +260,7 @@ private void WriteHeaderTableList(BinaryWriter bw)
                 bw.Write(ft.ToBytesClass());
         }
 
-        public string FilePath { get; set; }
+        public string? FilePath { get; set; }
         public bool Modified { get; set; }
         public Task<byte[][]> GetFiles() => Task.FromResult(DecompressedFiles);
         public Task<byte[]> GetFile(int file, int subFile = 0) => Task.FromResult(this[file]);
@@ -365,8 +365,8 @@ public class FileHashAbsolute
 
     public class FileHashFolder
     {
-        public FileHashFolderInfo Folder;
-        public FileHashIndex[] Files;
+        public FileHashFolderInfo Folder = new();
+        public FileHashIndex[] Files = Array.Empty<FileHashIndex>();
         public int GetIndexFileName(ulong hash) => Array.FindIndex(Files, z => z.HashFnv1aPathFileName == hash);
         public int GetIndexFileName(string name) => Array.FindIndex(Files, z => z.IsMatch(name));
     }
diff --git a/pkNX.Containers/NX/NSO.cs b/pkNX.Containers/NX/NSO.cs
index 894b4d08..0ecf9845 100644
--- a/pkNX.Containers/NX/NSO.cs
+++ b/pkNX.Containers/NX/NSO.cs
@@ -24,6 +24,7 @@ public class NSO
         public decimal CompressionRatioRO => (decimal)DecompressedRO.Length / CompressedRO.Length;
         public decimal CompressionRatioData => (decimal)DecompressedData.Length / CompressedData.Length;
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
         public NSO(BinaryReader br) => ReadHeader(br);
 
         public NSO(byte[] data)
@@ -32,6 +33,7 @@ public NSO(byte[] data)
             using var br = new BinaryReader(ms);
             ReadHeader(br);
         }
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 
         private void ReadHeader(BinaryReader br)
         {
diff --git a/pkNX.Containers/NX/NSOHeader.cs b/pkNX.Containers/NX/NSOHeader.cs
index d9325e31..d8d5fa28 100644
--- a/pkNX.Containers/NX/NSOHeader.cs
+++ b/pkNX.Containers/NX/NSOHeader.cs
@@ -16,6 +16,7 @@ public class NSOHeader
         public uint Reserved;
         public NSOFlag Flags;
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
         public SegmentHeader HeaderText;
         public int ModuleOffset;
         public SegmentHeader HeaderRO;
@@ -46,4 +47,5 @@ public class NSOHeader
         [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
         public byte[] HashData;
     }
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 }
\ No newline at end of file
diff --git a/pkNX.Containers/SARC/SARC.cs b/pkNX.Containers/SARC/SARC.cs
index 6556f64a..19b2f3a0 100644
--- a/pkNX.Containers/SARC/SARC.cs
+++ b/pkNX.Containers/SARC/SARC.cs
@@ -34,8 +34,10 @@ public SARC(IReadOnlyList<string> files, string baseFolder)
             Header = new SARCHeader();
             SFAT = new SFAT(baseFolder, files);
             SFNT = new SFNT();
+            Files = new byte[]?[SFAT.Entries.Count];
         }
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
         /// <summary>
         /// Initializes a <see cref="SARC"/> from a file location.
         /// </summary>
@@ -53,12 +55,15 @@ public SARC(IReadOnlyList<string> files, string baseFolder)
         /// </summary>
         /// <param name="br"></param>
         public SARC(BinaryReader br) => OpenRead(br);
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 
         /// <summary>
         /// Reads the contents of the <see cref="SARC"/> header and file info tables.
         /// </summary>
         protected override void Initialize()
         {
+            if (Reader is null)
+                throw new NullReferenceException(nameof(Reader));
             Header = new SARCHeader(Reader);
             if (!SigMatches)
                 return;
@@ -83,8 +88,8 @@ private void PackSARC(BinaryWriter bw, ContainerHandler handler, CancellationTok
             {
                 var entr = SFAT.Entries[i];
                 if (entr.FileName == null)
-                    entr.GetFileName(Reader.BaseStream, (int)currentStringOffset);
-                entr.WriteFileName(Reader.BaseStream, (int)SFNT.StringOffset);
+                    entr.GetFileName(Reader!.BaseStream, (int)currentStringOffset);
+                entr.WriteFileName(Reader!.BaseStream, (int)SFNT.StringOffset);
                 while (Reader.BaseStream.Position % 4 != 0)
                     bw.Write((byte)0);
             }
@@ -126,12 +131,12 @@ public override byte[] GetEntry(int index, int subFile)
             if (f.File is byte[] data)
                 return data;
 
-            data = f.GetFileData(Reader.BaseStream);
+            data = f.GetFileData(Reader!.BaseStream);
             f.File = data; // cache for future fetches
             return data;
         }
 
-        public override void Dump(string path, ContainerHandler handler)
+        public override void Dump(string? path, ContainerHandler handler)
         {
             path ??= FilePath;
             if (path == null)
@@ -149,12 +154,12 @@ public override void Dump(string path, ContainerHandler handler)
             handler.Initialize(count);
             for (int i = 0; i < count; i++)
             {
-                SFAT.Entries[i].Dump(Reader.BaseStream, path, Header.DataOffset);
+                SFAT.Entries[i].Dump(Reader!.BaseStream, path, Header.DataOffset);
                 handler.StepFile(i + 1);
             }
         }
 
-        public static SARC GetSARC(BinaryReader br)
+        public static SARC? GetSARC(BinaryReader br)
         {
             if (br.BaseStream.Length < 20)
                 return null;
diff --git a/pkNX.Containers/SARC/SFATEntry.cs b/pkNX.Containers/SARC/SFATEntry.cs
index b4e40fad..1f46f32d 100644
--- a/pkNX.Containers/SARC/SFATEntry.cs
+++ b/pkNX.Containers/SARC/SFATEntry.cs
@@ -11,7 +11,7 @@ public class SFATEntry : LargeContainerEntry
         public uint FileNameHash;
         public int FileNameOffset;
 
-        public string FileName { get; private set; }
+        public string? FileName { get; private set; }
 
         private static uint GetHash(string name, int length, uint multiplier)
         {
@@ -66,7 +66,7 @@ public void WriteFileName(Stream parent, int StringOffset)
         {
             FileNameOffset = (int)(parent.Position - StringOffset) / 4;
 
-            var str = FileName.Replace(Path.DirectorySeparatorChar, '/');
+            var str = FileName?.Replace(Path.DirectorySeparatorChar, '/') ?? string.Empty;
             foreach (var b in str)
                 parent.WriteByte((byte)b);
             parent.WriteByte(0); // \0
diff --git a/pkNX.Containers/SingleFileContainer.cs b/pkNX.Containers/SingleFileContainer.cs
index 184337d4..d137b560 100644
--- a/pkNX.Containers/SingleFileContainer.cs
+++ b/pkNX.Containers/SingleFileContainer.cs
@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -7,12 +8,12 @@ namespace pkNX.Containers
 {
     public class SingleFileContainer : IFileContainer
     {
-        public string FilePath { get; set; }
+        public string? FilePath { get; set; }
         public bool Modified { get; set; }
         public int Count => 1;
 
-        public byte[] Data;
-        private byte[] Backup;
+        public byte[] Data = Array.Empty<byte>();
+        private byte[] Backup = Array.Empty<byte>();
         public SingleFileContainer(byte[] data) => LoadData(data);
         public SingleFileContainer(BinaryReader br) => LoadData(br.ReadBytes((int) br.BaseStream.Length));
         public SingleFileContainer(string path) => LoadData(FileMitm.ReadAllBytes(FilePath = path));
@@ -39,6 +40,6 @@ public void CancelEdits()
         public Task<byte[]> GetFile(int file, int subFile = 0) => Task.FromResult(this[0]);
         public Task SetFile(int file, byte[] value, int subFile = 0) => Task.FromResult(Data = value);
         public Task SaveAs(string path, ContainerHandler handler, CancellationToken token) => new(() => Dump(path, handler), token);
-        public void Dump(string path, ContainerHandler handler) => FileMitm.WriteAllBytes(path ?? FilePath, Data);
+        public void Dump(string? path, ContainerHandler handler) => FileMitm.WriteAllBytes(path ?? FilePath!, Data);
     }
 }
diff --git a/pkNX.Containers/pkNX.Containers.csproj b/pkNX.Containers/pkNX.Containers.csproj
index 196cacb1..fefc8ef3 100644
--- a/pkNX.Containers/pkNX.Containers.csproj
+++ b/pkNX.Containers/pkNX.Containers.csproj
@@ -4,6 +4,7 @@
     <TargetFrameworks>netstandard2.0;net46</TargetFrameworks>
     <Description>Packing &amp; Unpacking</Description>
     <LangVersion>9</LangVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/pkNX.Randomization/Randomizers/FormRandomizer.cs b/pkNX.Randomization/Randomizers/FormRandomizer.cs
index 7342017e..581ccad2 100644
--- a/pkNX.Randomization/Randomizers/FormRandomizer.cs
+++ b/pkNX.Randomization/Randomizers/FormRandomizer.cs
@@ -14,7 +14,7 @@ public FormRandomizer(PersonalTable t)
             Personal = t;
         }
 
-        public int GetRandomForme(int species, bool mega, bool fused, bool alola, bool galar, PersonalInfo[] stats = null)
+        public int GetRandomForme(int species, bool mega, bool fused, bool alola, bool galar, PersonalInfo[]? stats = null)
         {
             stats ??= Personal.Table;
             if (stats[species].FormeCount <= 1)
@@ -48,7 +48,7 @@ public int GetRandomForme(int species, bool mega, bool fused, bool alola, bool g
                 case Darmanitan when galar:
                 {
                     int form = Util.Random.Next(stats[species].FormeCount);
-                    return form &= 2;
+                    return form & 2;
                 }
 
                 // some species have 1 invalid form among several other valid forms, handle them here
diff --git a/pkNX.Randomization/Randomizers/LearnsetRandomizer.cs b/pkNX.Randomization/Randomizers/LearnsetRandomizer.cs
index 2fd11259..e104d35e 100644
--- a/pkNX.Randomization/Randomizers/LearnsetRandomizer.cs
+++ b/pkNX.Randomization/Randomizers/LearnsetRandomizer.cs
@@ -14,9 +14,9 @@ public class LearnsetRandomizer : Randomizer
         private readonly GameInfo Game;
         private readonly PersonalTable Personal;
         private MoveRandomizer moverand;
-        public IReadOnlyList<Move> Moves { private get; set; }
+        public IReadOnlyList<Move> Moves { private get; set; } = Array.Empty<Move>();
 
-        public LearnSettings Settings { get; private set; }
+        public LearnSettings Settings { get; private set; } = new();
         public IList<int> BannedMoves { set => moverand.Settings.BannedMoves = value; }
 
         public LearnsetRandomizer(GameInfo game, Learnset[] learnsets, PersonalTable t)
@@ -24,6 +24,9 @@ public LearnsetRandomizer(GameInfo game, Learnset[] learnsets, PersonalTable t)
             Game = game;
             Learnsets = learnsets;
             Personal = t;
+
+            // temp, overwrite later if using it
+            moverand = new MoveRandomizer(game, Moves, Personal);
         }
 
         private static readonly int[] MetronomeMove = { 118 };
@@ -59,7 +62,7 @@ public void ExecuteExpandOnly()
             }
         }
 
-        public void Initialize(Move[] moves, LearnSettings settings, MovesetRandSettings moverandset, int[] bannedMoves = null)
+        public void Initialize(Move[] moves, LearnSettings settings, MovesetRandSettings moverandset, int[]? bannedMoves = null)
         {
             Moves = moves;
             Settings = settings;
diff --git a/pkNX.Randomization/Randomizers/MoveRandomizer.cs b/pkNX.Randomization/Randomizers/MoveRandomizer.cs
index 0b6e672d..282c481c 100644
--- a/pkNX.Randomization/Randomizers/MoveRandomizer.cs
+++ b/pkNX.Randomization/Randomizers/MoveRandomizer.cs
@@ -12,7 +12,7 @@ public class MoveRandomizer : Randomizer
         private readonly GameInfo Config;
 
         private GenericRandomizer<int> RandMove;
-        internal MovesetRandSettings Settings;
+        internal MovesetRandSettings Settings = new();
 
         public MoveRandomizer(GameInfo config, IReadOnlyList<Move> moves, PersonalTable t)
         {
diff --git a/pkNX.Randomization/Randomizers/Personal/PersonalRandomizer.cs b/pkNX.Randomization/Randomizers/Personal/PersonalRandomizer.cs
index 9475e92d..b1629b3f 100644
--- a/pkNX.Randomization/Randomizers/Personal/PersonalRandomizer.cs
+++ b/pkNX.Randomization/Randomizers/Personal/PersonalRandomizer.cs
@@ -17,7 +17,7 @@ public class PersonalRandomizer : Randomizer
         private readonly PersonalTable Table;
         private readonly EvolutionSet[] Evolutions;
 
-        public PersonalRandSettings Settings { get; set; }
+        public PersonalRandSettings Settings { get; set; } = new();
 
         public PersonalRandomizer(PersonalTable table, GameInfo game, EvolutionSet[] evolutions)
         {
@@ -47,7 +47,7 @@ private void RandomizeAllSpecies()
                 RandomizeSpecies(species);
         }
 
-        private bool[] processed;
+        private bool[] processed = Array.Empty<bool>();
 
         private void RandomizeChains()
         {
@@ -61,9 +61,12 @@ private void RandomizeChains()
 
         private bool AlreadyProcessed(int index)
         {
-            if (processed[index])
+            var p = processed;
+            if (p.Length <= index)
+                return false;
+            if (p[index])
                 return true;
-            processed[index] = true;
+            p[index] = true;
             return false;
         }
 
diff --git a/pkNX.Randomization/Randomizers/SpeciesRandomizer.cs b/pkNX.Randomization/Randomizers/SpeciesRandomizer.cs
index 90149175..9fb8d1cf 100644
--- a/pkNX.Randomization/Randomizers/SpeciesRandomizer.cs
+++ b/pkNX.Randomization/Randomizers/SpeciesRandomizer.cs
@@ -1,4 +1,5 @@
-using System.Linq;
+using System;
+using System.Linq;
 using pkNX.Structures;
 
 namespace pkNX.Randomization
@@ -9,7 +10,7 @@ public class SpeciesRandomizer
         private readonly int MaxSpeciesID;
         private readonly GameInfo Game;
 
-        private SpeciesSettings s;
+        private SpeciesSettings s = new();
 
         public SpeciesRandomizer(GameInfo game, PersonalTable t)
         {
@@ -31,7 +32,7 @@ public void Initialize(SpeciesSettings settings, params int[] banlist)
         }
 
         #region Random Species Filtering Parameters
-        private GenericRandomizer<int> RandSpec;
+        private GenericRandomizer<int> RandSpec = new(Array.Empty<int>());
         private int loopctr;
         private const int l = 10; // tweakable scalars
         private const int h = 11;
diff --git a/pkNX.Randomization/Randomizers/TrainerRandomizer.cs b/pkNX.Randomization/Randomizers/TrainerRandomizer.cs
index ed0b57f5..1c08ddc9 100644
--- a/pkNX.Randomization/Randomizers/TrainerRandomizer.cs
+++ b/pkNX.Randomization/Randomizers/TrainerRandomizer.cs
@@ -17,17 +17,19 @@ public class TrainerRandomizer : Randomizer
         private readonly IList<int> SpecialClasses;
         private readonly IList<int> CrashClasses;
 
-        public GenericRandomizer<int> Class { get; set; }
-        public LearnsetRandomizer Learn { get; set; }
-        public SpeciesRandomizer RandSpec { get; set; }
-        public FormRandomizer RandForm { get; set; }
-        public MoveRandomizer RandMove { get; set; }
         public int ClassCount { get; set; }
-        public Func<TrainerPoke> GetBlank { get; set; }
-        public EvolutionSet[] Evos { get; set; }
+        public EvolutionSet[] Evos { get; }
 
-        private TrainerRandSettings Settings;
-        private SpeciesSettings SpecSettings;
+        // Set these before starting up
+        public GenericRandomizer<int> Class { get; set; } = null!;
+        public LearnsetRandomizer Learn { get; set; } = null!;
+        public SpeciesRandomizer RandSpec { get; set; } = null!;
+        public FormRandomizer RandForm { get; set; } = null!;
+        public MoveRandomizer RandMove { get; set; } = null!;
+        public Func<TrainerPoke> GetBlank { get; set; } = null!;
+
+        private TrainerRandSettings Settings = null!;
+        private SpeciesSettings SpecSettings = null!;
 
         public TrainerRandomizer(GameInfo info, PersonalTable t, VsTrainer[] trainers, EvolutionSet[] evos)
         {
diff --git a/pkNX.Randomization/Util.cs b/pkNX.Randomization/Util.cs
index 3ff85270..3c53ec61 100644
--- a/pkNX.Randomization/Util.cs
+++ b/pkNX.Randomization/Util.cs
@@ -28,15 +28,19 @@ public static void Shuffle<T>(IList<T> array)
             }
         }
 
-        public static int ToInt32(string value)
+        public static int ToInt32(string? value)
         {
-            string val = value?.Replace(" ", "").Replace("_", "").Trim();
+            if (value is null)
+                return 0;
+            string val = value.Replace(" ", "").Replace("_", "").Trim();
             return string.IsNullOrWhiteSpace(val) ? 0 : int.Parse(val);
         }
 
-        public static uint ToUInt32(string value)
+        public static uint ToUInt32(string? value)
         {
-            string val = value?.Replace(" ", "").Replace("_", "").Trim();
+            if (value is null)
+                return 0;
+            string val = value.Replace(" ", "").Replace("_", "").Trim();
             return string.IsNullOrWhiteSpace(val) ? 0 : uint.Parse(val);
         }
 
diff --git a/pkNX.Randomization/pkNX.Randomization.csproj b/pkNX.Randomization/pkNX.Randomization.csproj
index be2421bc..2be3af3d 100644
--- a/pkNX.Randomization/pkNX.Randomization.csproj
+++ b/pkNX.Randomization/pkNX.Randomization.csproj
@@ -4,6 +4,7 @@
     <TargetFrameworks>netstandard2.0;net46</TargetFrameworks>
     <Description>Randomizer Utility</Description>
     <LangVersion>9</LangVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/pkNX.Sprites/ImageUtil.cs b/pkNX.Sprites/ImageUtil.cs
index 1282852e..fc9633ab 100644
--- a/pkNX.Sprites/ImageUtil.cs
+++ b/pkNX.Sprites/ImageUtil.cs
@@ -19,8 +19,6 @@ public static Bitmap LayerImage(Image baseLayer, Image overLayer, int x, int y,
 
         public static Bitmap LayerImage(Image baseLayer, Image overLayer, int x, int y)
         {
-            if (baseLayer is null)
-                return (Bitmap)overLayer;
             Bitmap img = new(baseLayer);
             using Graphics gr = Graphics.FromImage(img);
             gr.DrawImage(overLayer, x, y, overLayer.Width, overLayer.Height);
diff --git a/pkNX.Structures/Evolution/EvolutionSet.cs b/pkNX.Structures/Evolution/EvolutionSet.cs
index 0290df3d..661393ea 100644
--- a/pkNX.Structures/Evolution/EvolutionSet.cs
+++ b/pkNX.Structures/Evolution/EvolutionSet.cs
@@ -1,4 +1,6 @@
-namespace pkNX.Structures
+using System;
+
+namespace pkNX.Structures
 {
     /// <summary>
     /// Table of Evolution Branch Entries
@@ -7,5 +9,7 @@ public abstract class EvolutionSet
     {
         public EvolutionMethod[] PossibleEvolutions;
         public abstract byte[] Write();
+
+        protected EvolutionSet() => PossibleEvolutions = Array.Empty<EvolutionMethod>();
     }
 }
diff --git a/pkNX.Structures/Learnset/Learnset.cs b/pkNX.Structures/Learnset/Learnset.cs
index cddecd4a..1d83faa8 100644
--- a/pkNX.Structures/Learnset/Learnset.cs
+++ b/pkNX.Structures/Learnset/Learnset.cs
@@ -10,6 +10,12 @@ public abstract class Learnset
         public int[] Moves { get; protected set; }
         public int[] Levels { get; protected set; }
 
+        protected Learnset()
+        {
+            Moves = Array.Empty<int>();
+            Levels = Array.Empty<int>();
+        }
+
         public abstract byte[] Write();
 
         /// <summary>
diff --git a/pkNX.Structures/Scripts/AmxHeader.cs b/pkNX.Structures/Scripts/AmxHeader.cs
index f524e955..5a757a54 100644
--- a/pkNX.Structures/Scripts/AmxHeader.cs
+++ b/pkNX.Structures/Scripts/AmxHeader.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Runtime.InteropServices;
 
 namespace pkNX.Structures
diff --git a/pkNX.WinForms/Controls/EncounterList.cs b/pkNX.WinForms/Controls/EncounterList.cs
index bbf09a7d..6c7e3f6a 100644
--- a/pkNX.WinForms/Controls/EncounterList.cs
+++ b/pkNX.WinForms/Controls/EncounterList.cs
@@ -89,8 +89,8 @@ private void UpdateRowImage(int row)
             dgv.Rows[row].Cells[0].Value = SpriteUtil.GetSprite(sp, form, 0, 0, false, false, false);
         }
 
-        private EncounterSlot7b[] Slots;
-        public static string[] species;
+        private EncounterSlot7b[]? Slots;
+        public static string[] species = Array.Empty<string>();
 
         public void LoadSlots(EncounterSlot7b[] slots)
         {
diff --git a/pkNX.WinForms/Controls/EncounterList8.cs b/pkNX.WinForms/Controls/EncounterList8.cs
index d2f2fcd7..f60bae42 100644
--- a/pkNX.WinForms/Controls/EncounterList8.cs
+++ b/pkNX.WinForms/Controls/EncounterList8.cs
@@ -79,8 +79,8 @@ private void UpdateRowImage(int row)
             dgv.Rows[row].Cells[0].Value = SpriteUtil.GetSprite(sp, form, 0, 0, false, false, false);
         }
 
-        private EncounterSlot8[] Slots;
-        public static string[] species;
+        private EncounterSlot8[]? Slots;
+        public static string[] species = Array.Empty<string>();
 
         public void LoadSlots(EncounterSlot8[] slots)
         {
diff --git a/pkNX.WinForms/Controls/EvolutionRow.cs b/pkNX.WinForms/Controls/EvolutionRow.cs
index b46bc48e..a3f6899e 100644
--- a/pkNX.WinForms/Controls/EvolutionRow.cs
+++ b/pkNX.WinForms/Controls/EvolutionRow.cs
@@ -42,7 +42,7 @@ public EvolutionRow()
 
         private void ChangeSpecies(int spec, int form) => PB_Preview.Image = SpriteUtil.GetSprite(spec, form, 0, 0, false, false, false);
 
-        private EvolutionMethod current;
+        private EvolutionMethod? current;
         private EvolutionTypeArgumentType oldMethod;
 
         public void LoadEvolution(EvolutionMethod s)
@@ -58,6 +58,8 @@ public void LoadEvolution(EvolutionMethod s)
         public void SaveEvolution()
         {
             var evo = current;
+            if (evo == null)
+                return;
             evo.Species = CB_Species.SelectedIndex;
             evo.Form = (int)NUD_Form.Value;
             evo.Level = (int)NUD_Level.Value;
@@ -65,10 +67,10 @@ public void SaveEvolution()
             evo.Argument = CB_Arg.SelectedIndex;
         }
 
-        public static string[] items;
-        public static string[] movelist;
-        public static string[] species;
-        public static string[] types;
+        public static string[] items = Array.Empty<string>();
+        public static string[] movelist = Array.Empty<string>();
+        public static string[] species = Array.Empty<string>();
+        public static string[] types = Array.Empty<string>();
 
         private static readonly string[] EvoMethods = Enum.GetNames(typeof(EvolutionType));
         private static readonly string[] Levels = Enumerable.Range(0, 100 + 1).Select(z => z.ToString()).ToArray();
diff --git a/pkNX.WinForms/Controls/MegaEvoEntry.cs b/pkNX.WinForms/Controls/MegaEvoEntry.cs
index cc40cfd6..4cbf59f4 100644
--- a/pkNX.WinForms/Controls/MegaEvoEntry.cs
+++ b/pkNX.WinForms/Controls/MegaEvoEntry.cs
@@ -7,7 +7,7 @@ namespace pkNX.WinForms
 {
     public partial class MegaEvoEntry : UserControl
     {
-        public static string[] items;
+        public static string[] items = Array.Empty<string>();
 
         private static readonly string[] EvoMethods = Enum.GetNames(typeof(MegaEvolutionMethod));
 
@@ -27,7 +27,7 @@ public MegaEvoEntry()
         }
 
         public int Species { private get; set; }
-        private MegaEvolutionSet current;
+        private MegaEvolutionSet? current;
 
         private void ChangeSpecies(int form)
         {
@@ -47,6 +47,9 @@ public void LoadEvolution(MegaEvolutionSet s, int species)
 
         public void SaveEvolution()
         {
+            if (current == null)
+                return;
+            
             if (CB_Method.SelectedIndex <= 0)
             {
                 current.ToForm = 0;
diff --git a/pkNX.WinForms/Controls/StatEditor.cs b/pkNX.WinForms/Controls/StatEditor.cs
index ffb4977b..0583434b 100644
--- a/pkNX.WinForms/Controls/StatEditor.cs
+++ b/pkNX.WinForms/Controls/StatEditor.cs
@@ -26,9 +26,9 @@ public void Initialize(string[] types)
             UpdatingFields = false;
         }
 
-        public PersonalTable Personal { private get; set; }
+        public PersonalTable? Personal { private get; set; }
         public bool UpdatingFields;
-        public StatPKM PKM { get; set; }
+        public StatPKM PKM { get; set; } = new TrainerPoke7b();
 
         private readonly MaskedTextBox[] tb_iv;
         private readonly MaskedTextBox[] tb_ev;
@@ -52,7 +52,11 @@ public void UpdateStats()
             }
             UpdatingFields = false;
 
-            var pi = Personal.GetFormeEntry(PKM.Species, PKM.Form);
+            var pt = Personal;
+            if (pt == null)
+                throw new NullReferenceException("Personal table hasn't been initialized.");
+
+            var pi = pt.GetFormeEntry(PKM.Species, PKM.Form);
             var stats = PKM.GetStats(pi);
 
             Stat_HP.Text = stats[0].ToString();
diff --git a/pkNX.WinForms/Main.cs b/pkNX.WinForms/Main.cs
index 95560a8e..e57e9285 100644
--- a/pkNX.WinForms/Main.cs
+++ b/pkNX.WinForms/Main.cs
@@ -17,7 +17,7 @@ private int Language
             set => CB_Lang.SelectedIndex = value;
         }
 
-        private EditorBase Editor;
+        private EditorBase? Editor;
 
         public Main()
         {
diff --git a/pkNX.WinForms/MainEditor/EditUtil.cs b/pkNX.WinForms/MainEditor/EditUtil.cs
index c683d21d..337b959f 100644
--- a/pkNX.WinForms/MainEditor/EditUtil.cs
+++ b/pkNX.WinForms/MainEditor/EditUtil.cs
@@ -20,7 +20,7 @@ public class SharedSettings
 
     public static class EditUtil
     {
-        public static SharedSettings Settings { get; set; }
+        public static SharedSettings Settings { get; set; } = new();
 
         public static void LoadSettings(GameVersion game)
         {
@@ -35,7 +35,7 @@ public static void LoadSettings(GameVersion game)
             var reader = new XmlSerializer(typeof(SharedSettings));
             try
             {
-                Settings = (SharedSettings) reader.Deserialize(file) ?? new SharedSettings();
+                Settings = (SharedSettings?) reader.Deserialize(file) ?? new SharedSettings();
             }
             catch (Exception e)
             {
diff --git a/pkNX.WinForms/MainEditor/EditorProvider.cs b/pkNX.WinForms/MainEditor/EditorProvider.cs
index 9ed24d0e..2a5f78fc 100644
--- a/pkNX.WinForms/MainEditor/EditorProvider.cs
+++ b/pkNX.WinForms/MainEditor/EditorProvider.cs
@@ -14,7 +14,7 @@ public abstract class EditorBase
         public int Language { get => ROM.Language; set => ROM.Language = value; }
 
         protected EditorBase(GameManager rom) => ROM = rom;
-        public string Location { get; internal set; }
+        public string? Location { get; internal set; }
 
         public IEnumerable<Button> GetControls(int width, int height)
         {
@@ -41,7 +41,7 @@ public IEnumerable<Button> GetControls(int width, int height)
 
         public void Close() => ROM.SaveAll(true);
 
-        private static EditorBase GetEditor(GameManager ROM)
+        private static EditorBase? GetEditor(GameManager ROM)
         {
             var g = ROM.Game;
             if (GameVersion.XY.Contains(g)) return new EditorXY(ROM);
@@ -55,13 +55,17 @@ private static EditorBase GetEditor(GameManager ROM)
             return null;
         }
 
-        public static EditorBase GetEditor(string loc, int language)
+        public static EditorBase? GetEditor(string loc, int language)
         {
             var gl = GameLocation.GetGame(loc);
             if (gl == null)
                 return null;
-            GameManager gm = GameManager.GetManager(gl, language);
-            EditorBase editor = GetEditor(gm);
+
+            var gm = GameManager.GetManager(gl, language);
+            var editor = GetEditor(gm);
+            if (editor == null)
+                return null;
+
             editor.Location = loc;
             return editor;
         }
diff --git a/pkNX.WinForms/Ripper/FileRipper.cs b/pkNX.WinForms/Ripper/FileRipper.cs
index d8917b15..174d7391 100644
--- a/pkNX.WinForms/Ripper/FileRipper.cs
+++ b/pkNX.WinForms/Ripper/FileRipper.cs
@@ -67,7 +67,7 @@ private static FileRipperResult GFPackDump(BinaryReader br, uint header, string
             return new FileRipperResult(RipResultCode.Success) {ResultPath = resultPath};
         }
 
-        public static FileRipperResult TryOpenFile(string path, ContainerHandler handler = null)
+        public static FileRipperResult TryOpenFile(string path, ContainerHandler? handler = null)
         {
             if (!File.Exists(path))
                 return new FileRipperResult(RipResultCode.FileExist);
@@ -115,7 +115,7 @@ private static FileRipperResult TryLoadFile(BinaryReader br, uint header, string
     public class FileRipperResult
     {
         public readonly RipResultCode Code;
-        public string ResultPath;
+        public string? ResultPath;
 
         public FileRipperResult(RipResultCode code) => Code = code;
     }
diff --git a/pkNX.WinForms/Subforms/BTTE.cs b/pkNX.WinForms/Subforms/BTTE.cs
index aae9e0df..33194764 100644
--- a/pkNX.WinForms/Subforms/BTTE.cs
+++ b/pkNX.WinForms/Subforms/BTTE.cs
@@ -16,9 +16,12 @@ namespace pkNX.WinForms
     public partial class BTTE : Form
     {
         private readonly LearnsetRandomizer learn;
-        private string[][] AltForms;
+        private readonly string[][] AltForms;
+        private readonly PictureBox[] pba;
+
         private int entry = -1;
-        private PictureBox[] pba;
+        private TrainerPoke pkm = new TrainerPoke7b();
+        private bool loadingPKM;
 
         private readonly PersonalTable Personal;
         private readonly GameManager Game;
@@ -38,12 +41,16 @@ public partial class BTTE : Form
         public BTTE(GameManager game, TrainerEditor editor)
         {
             InitializeComponent();
+            pba = new[] { PB_Team1, PB_Team2, PB_Team3, PB_Team4, PB_Team5, PB_Team6 };
 
             Stats.Personal = Personal = game.Data.PersonalData;
             Game = game;
             Trainers = editor;
             learn = new LearnsetRandomizer(game.Info, game.Data.LevelUpData.LoadAll(), Personal);
 
+            AltForms = new byte[Personal.TableLength]
+                .Select(_ => Enumerable.Range(0, 32).Select(i => i.ToString()).ToArray()).ToArray();
+
             trClass = Game.GetStrings(TextName.TrainerClasses);
             trName = Game.GetStrings(TextName.TrainerClasses);
 
@@ -225,11 +232,9 @@ private void RefreshPKMSlotAbility()
 
         private void Setup()
         {
-            AltForms = new byte[Personal.TableLength]
-                .Select(_ => Enumerable.Range(0, 32).Select(i => i.ToString()).ToArray()).ToArray();
             CB_TrainerID.Items.Clear();
             for (int i = 0; i < Trainers.Length; i++)
-                CB_TrainerID.Items.Add(GetEntryTitle(trName[i] ?? "UNKNOWN", i));
+                CB_TrainerID.Items.Add(GetEntryTitle(trName[i], i));
 
             CB_Trainer_Class.Items.Clear();
             for (int i = 0; i < trClass.Length; i++)
@@ -237,7 +242,6 @@ private void Setup()
 
             specieslist[0] = "---";
             abilitylist[0] = itemlist[0] = movelist[0] = "(None)";
-            pba = new[] {PB_Team1, PB_Team2, PB_Team3, PB_Team4, PB_Team5, PB_Team6};
 
             CB_Species.Items.AddRange(specieslist);
 
@@ -270,7 +274,6 @@ private void Setup()
 
             CB_TrainerID.SelectedIndex = 0;
             entry = 0;
-            pkm = new TrainerPoke7b();
             PopulateFields(pkm);
         }
 
@@ -312,10 +315,6 @@ private void UpdateTrainerName(object sender, EventArgs e)
             CB_TrainerID.Items[entry] = GetEntryTitle(str, entry);
         }
 
-        private TrainerPoke pkm;
-
-        private bool loadingPKM;
-
         private void PopulateFields(TrainerPoke pk)
         {
             pkm = pk.Clone();
diff --git a/pkNX.WinForms/Subforms/GGWE.cs b/pkNX.WinForms/Subforms/GGWE.cs
index 747133b3..eacb60ed 100644
--- a/pkNX.WinForms/Subforms/GGWE.cs
+++ b/pkNX.WinForms/Subforms/GGWE.cs
@@ -18,7 +18,7 @@ public sealed partial class GGWE : Form
         public GGWE(GameManager rom, EncounterArchive7b obj)
         {
             InitializeComponent();
-            if (obj?.EncounterTables?[0]?.GroundTable == null)
+            if (obj.EncounterTables.Length == 0 || obj.EncounterTables[0].GroundTable.Length == 0)
             {
                 WinFormsUtil.Error("Bad data provided.", $"Unable to parse to {nameof(EncounterArchive7b)} data.");
                 Close();
@@ -80,7 +80,7 @@ private static IEnumerable<string> GetNames(IEnumerable<ulong> locs, string[] lo
         private static IEnumerable<string> GetScreenedNames(IEnumerable<string> names)
         {
             int ctr = 0;
-            string prev = null;
+            string? prev = null;
             foreach (var name in names)
             {
                 if (name != prev)
diff --git a/pkNX.WinForms/Subforms/GenericEditor.cs b/pkNX.WinForms/Subforms/GenericEditor.cs
index 9cacee48..4754a61d 100644
--- a/pkNX.WinForms/Subforms/GenericEditor.cs
+++ b/pkNX.WinForms/Subforms/GenericEditor.cs
@@ -7,7 +7,7 @@ namespace pkNX.WinForms
 {
     public sealed partial class GenericEditor<T> : Form where T : class
     {
-        public GenericEditor(DataCache<T> cache, string[] names, string title, Action randomize = null)
+        public GenericEditor(DataCache<T> cache, string[] names, string title, Action? randomize = null)
         {
             InitializeComponent();
             Cache = cache;
diff --git a/pkNX.WinForms/Subforms/PokeDataUI.cs b/pkNX.WinForms/Subforms/PokeDataUI.cs
index 8924d5a3..f1978f69 100644
--- a/pkNX.WinForms/Subforms/PokeDataUI.cs
+++ b/pkNX.WinForms/Subforms/PokeDataUI.cs
@@ -14,6 +14,8 @@ namespace pkNX.WinForms
 {
     public partial class PokeDataUI : Form
     {
+        private readonly bool Loaded;
+
         public PokeDataUI(PokeEditor editor, GameManager rom)
         {
             ROM = rom;
@@ -36,6 +38,10 @@ public PokeDataUI(PokeEditor editor, GameManager rom)
             abilities[0] = items[0] = movelist[0] = "";
 
             var pt = ROM.Data.PersonalData;
+            cPersonal = pt[0];
+            cLearnset = Editor.Learn[0];
+            cEvos = Editor.Evolve[0];
+            cMega = Editor.Mega.Length > 0 ? Editor.Mega[0] : Array.Empty<MegaEvolutionSet>();
 
             var altForms = pt.GetFormList(species, pt.MaxSpeciesID);
             entryNames = pt.GetPersonalEntryList(altForms, species, pt.MaxSpeciesID, out baseForms, out formVal);
@@ -45,10 +51,10 @@ public PokeDataUI(PokeEditor editor, GameManager rom)
 
             InitEvo(Editor.Evolve[0].PossibleEvolutions.Length);
 
-            if (Editor.Mega != null)
-                InitMega(2);
+            Megas = Editor.Mega != null ? InitMega(2) : Array.Empty<MegaEvoEntry>();
 
             CB_Species.SelectedIndex = 1;
+            Loaded = true;
 
             PG_Personal.SelectedObject = EditUtil.Settings.Personal;
             PG_Evolution.SelectedObject = EditUtil.Settings.Species;
@@ -78,6 +84,7 @@ public PokeDataUI(PokeEditor editor, GameManager rom)
         public Learnset cLearnset;
         public EvolutionSet cEvos;
         public MegaEvolutionSet[] cMega;
+        private readonly MegaEvoEntry[] Megas;
 
         public void InitPersonal()
         {
@@ -138,7 +145,7 @@ public void InitLearn()
                 dgvLevel.Width = 45;
                 dgvLevel.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter;
             }
-            DataGridViewComboBoxColumn dgvMove = new DataGridViewComboBoxColumn();
+            DataGridViewComboBoxColumn dgvMove = new();
             {
                 dgvMove.HeaderText = "Move";
                 dgvMove.DisplayIndex = 1;
@@ -152,7 +159,7 @@ public void InitLearn()
             dgv.Columns.Add(dgvMove);
         }
 
-        private static EvolutionRow[] EvoRows;
+        private static EvolutionRow[] EvoRows = Array.Empty<EvolutionRow>();
 
         public void InitEvo(int rows)
         {
@@ -171,24 +178,24 @@ public void InitEvo(int rows)
             }
         }
 
-        private MegaEvoEntry[] Megas;
-
-        public void InitMega(int count)
+        public MegaEvoEntry[] InitMega(int count)
         {
-            Megas = new MegaEvoEntry[count];
+            var result = new MegaEvoEntry[count];
             MegaEvoEntry.items = items;
 
             for (int i = 0; i < count; i++)
             {
                 var row = new MegaEvoEntry();
                 flowLayoutPanel1.Controls.Add(row);
-                Megas[i] = row;
+                result[i] = row;
             }
+
+            return result;
         }
 
         public void UpdateIndex(object sender, EventArgs e)
         {
-            if (cPersonal != null)
+            if (Loaded)
                 SaveCurrent();
             LoadIndex(CB_Species.SelectedIndex);
         }
@@ -205,7 +212,7 @@ private void LoadIndex(int index)
             if (Editor.Mega != null)
                 LoadMegas(Editor.Mega[index], spec);
             Bitmap rawImg = (Bitmap)SpriteUtil.GetSprite(spec, form, 0, 0, false, false, false);
-            Bitmap bigImg = new Bitmap(rawImg.Width * 2, rawImg.Height * 2);
+            Bitmap bigImg = new(rawImg.Width * 2, rawImg.Height * 2);
             for (int x = 0; x < rawImg.Width; x++)
             {
                 for (int y = 0; y < rawImg.Height; y++)
@@ -403,8 +410,8 @@ public void LoadLearnset(Learnset pkm)
         public void SaveLearnset()
         {
             var pkm = cLearnset;
-            List<int> moves = new List<int>();
-            List<int> levels = new List<int>();
+            List<int> moves = new();
+            List<int> levels = new();
             for (int i = 0; i < dgv.Rows.Count - 1; i++)
             {
                 int move = Array.IndexOf(movelist, dgv.Rows[i].Cells[1].Value);
diff --git a/pkNX.WinForms/Subforms/SSWE.cs b/pkNX.WinForms/Subforms/SSWE.cs
index cbb5fc50..19513c62 100644
--- a/pkNX.WinForms/Subforms/SSWE.cs
+++ b/pkNX.WinForms/Subforms/SSWE.cs
@@ -232,10 +232,10 @@ private void TC_Tables_DrawItem(object sender, DrawItemEventArgs e)
             }
 
             // Use our own font.
-            Font _tabFont = new Font("Arial", (float)10.0, FontStyle.Bold, GraphicsUnit.Pixel);
+            Font _tabFont = new("Arial", (float)10.0, FontStyle.Bold, GraphicsUnit.Pixel);
 
             // Draw string. Center the text.
-            StringFormat _stringFlags = new StringFormat
+            StringFormat _stringFlags = new()
             {
                 Alignment = StringAlignment.Center,
                 LineAlignment = StringAlignment.Center
diff --git a/pkNX.WinForms/Subforms/ShinyRate.cs b/pkNX.WinForms/Subforms/ShinyRate.cs
index 97761311..4ddbcbb5 100644
--- a/pkNX.WinForms/Subforms/ShinyRate.cs
+++ b/pkNX.WinForms/Subforms/ShinyRate.cs
@@ -26,8 +26,8 @@ public ShinyRate(ShinyRateInfo info)
                 RB_Default.Checked = true;
 
             // force update labels
-            ChangePercent(null, null);
-            ChangeRerollCount(null, null);
+            ChangePercent(this, EventArgs.Empty);
+            ChangeRerollCount(this, EventArgs.Empty);
             Loaded = true;
         }
 
diff --git a/pkNX.WinForms/Subforms/TMList.cs b/pkNX.WinForms/Subforms/TMList.cs
index 9ffc899f..004d3885 100644
--- a/pkNX.WinForms/Subforms/TMList.cs
+++ b/pkNX.WinForms/Subforms/TMList.cs
@@ -23,7 +23,7 @@ public TMList(ushort[] moves, int[] allowed, string[] movenames)
         }
 
         public bool Modified { get; set; }
-        public ushort[] FinalMoves { get; private set; }
+        public ushort[] FinalMoves { get; private set; } = Array.Empty<ushort>();
 
         private void SetupDGV(string[] list)
         {
diff --git a/pkNX.WinForms/Subforms/TextContainer.cs b/pkNX.WinForms/Subforms/TextContainer.cs
index b315e22f..994d82a6 100644
--- a/pkNX.WinForms/Subforms/TextContainer.cs
+++ b/pkNX.WinForms/Subforms/TextContainer.cs
@@ -7,12 +7,12 @@ namespace pkNX.WinForms
     public class TextContainer
     {
         public readonly IFileContainer Container;
-        public readonly TextConfig Config;
+        public readonly TextConfig? Config;
         public bool Remap { get; set; }
 
-        private readonly string[][] Cache;
+        private readonly string[]?[] Cache;
 
-        public TextContainer(IFileContainer c, TextConfig t = null, bool remap = false)
+        public TextContainer(IFileContainer c, TextConfig? t = null, bool remap = false)
         {
             Remap = remap;
             Config = t;
diff --git a/pkNX.WinForms/Subforms/TextEditor.cs b/pkNX.WinForms/Subforms/TextEditor.cs
index c6244740..8a2ef308 100644
--- a/pkNX.WinForms/Subforms/TextEditor.cs
+++ b/pkNX.WinForms/Subforms/TextEditor.cs
@@ -60,13 +60,13 @@ private void B_Import_Click(object sender, EventArgs e)
                 return;
 
             // Reload the form with the new data.
-            ChangeEntry(null, null);
+            ChangeEntry(this, e);
             WinFormsUtil.Alert("Imported Text from Input Path:", path);
         }
 
         public static void ExportTextFile(string fileName, bool newline, TextContainer lineData)
         {
-            using MemoryStream ms = new MemoryStream();
+            using MemoryStream ms = new();
             ms.Write(new byte[] {0xFF, 0xFE}, 0, 2); // Write Unicode BOM
             using (TextWriter tw = new StreamWriter(ms, new UnicodeEncoding()))
             {
@@ -88,7 +88,6 @@ private static void WriteTextFile(TextWriter tw, string fn, string[] data, bool
             tw.WriteLine("Text File : " + fn);
             tw.WriteLine("~~~~~~~~~~~~~~~");
             // Write the String to the File
-            if (data == null) return;
             foreach (string line in data)
             {
                 tw.WriteLine(newline
@@ -130,7 +129,7 @@ private bool ImportTextFiles(string fileName)
                 // else pray that the filename index lines up
 
                 i += 2; // Skip over the other header line
-                List<string> Lines = new List<string>();
+                List<string> Lines = new();
                 while (i < fileText.Length && fileText[i] != "~~~~~~~~~~~~~~~")
                 {
                     Lines.Add(fileText[i]);
@@ -166,7 +165,7 @@ private bool ImportTextFiles(string fileName)
         private void ChangeEntry(object sender, EventArgs e)
         {
             // Save All the old text
-            if (entry > -1 && sender != null)
+            if (entry > -1 && sender != this)
             {
                 try
                 {
@@ -189,7 +188,7 @@ private void SetStringsDataGridView(string[] textArray)
             dgv.Rows.Clear();
             // Clear the header columns, these are repopulated every time.
             dgv.Columns.Clear();
-            if (textArray == null || textArray.Length == 0)
+            if (textArray.Length == 0)
                 return;
             // Reset settings and columns.
             dgv.AllowUserToResizeColumns = false;
@@ -203,7 +202,7 @@ private void SetStringsDataGridView(string[] textArray)
             };
             dgvLine.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleRight;
 
-            DataGridViewTextBoxColumn dgvText = new DataGridViewTextBoxColumn
+            DataGridViewTextBoxColumn dgvText = new()
             {
                 HeaderText = "Text",
                 DisplayIndex = 1,
@@ -310,7 +309,7 @@ private void B_Randomize_Click(object sender, EventArgs e)
             int end = all ? TextData.Length - 1 : entry;
 
             // Gather strings
-            List<string> strings = new List<string>();
+            List<string> strings = new();
             for (int i = start; i <= end; i++)
             {
                 string[] data = TextData[i];
diff --git a/pkNX.WinForms/WinFormsUtil.cs b/pkNX.WinForms/WinFormsUtil.cs
index 6a0d2e5e..d54209a2 100644
--- a/pkNX.WinForms/WinFormsUtil.cs
+++ b/pkNX.WinForms/WinFormsUtil.cs
@@ -35,6 +35,6 @@ internal static DialogResult Prompt(MessageBoxButtons btn, params string[] lines
         /// Gets the selected value of the input <see cref="cb"/>. If no value is selected, will return 0.
         /// </summary>
         /// <param name="cb">ComboBox to retrieve value for.</param>
-        internal static int GetIndex(ComboBox cb) => (int)(cb?.SelectedValue ?? 0);
+        internal static int GetIndex(ComboBox cb) => (int)(cb.SelectedValue ?? 0);
     }
 }
\ No newline at end of file
diff --git a/pkNX.WinForms/pkNX.WinForms.csproj b/pkNX.WinForms/pkNX.WinForms.csproj
index 58e37e9f..e490bcfd 100644
--- a/pkNX.WinForms/pkNX.WinForms.csproj
+++ b/pkNX.WinForms/pkNX.WinForms.csproj
@@ -12,6 +12,7 @@
     <StartupObject>pkNX.WinForms.Program</StartupObject>
     <AssemblyName>pkNX</AssemblyName>
     <LangVersion>9</LangVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>