Added an error message to Script Editor for missing usescript references

+ Script save file functions now return true when everything was saved correctly, false otherwise
+ Return value of the script save functions is checked to determine whether or not to mark current script file as changed

DS_Map/Main Window.cs

@@ -6876,9 +6876,10 @@ namespace DSPRE {
             } else if (userEdited.fileID == int.MaxValue) {
                 MessageBox.Show("This " + typeof(ScriptFile).Name + " is couldn't be saved since it's empty.", "Can't save", MessageBoxButtons.OK, MessageBoxIcon.Warning);
             } else { //check if ScriptFile instance was created succesfully
-                userEdited.SaveToFileDefaultDir(selectScriptFileComboBox.SelectedIndex);
-                currentScriptFile = userEdited;
-                ScriptEditorSetClean();
+                if (userEdited.SaveToFileDefaultDir(selectScriptFileComboBox.SelectedIndex)) {
+                    currentScriptFile = userEdited;
+                    ScriptEditorSetClean();
+                }
             }
         }
         private void clearCurrentLevelScriptButton_Click(object sender, EventArgs e) {

DS_Map/ROMFiles/RomFile.cs

@@ -6,12 +6,12 @@ using static DSPRE.RomInfo;
 namespace DSPRE.ROMFiles {
     public abstract class RomFile {
         public abstract byte[] ToByteArray();
-        public void SaveToFile(string path, bool showSuccessMessage = true) {
+        public bool SaveToFile(string path, bool showSuccessMessage = true) {
             
             byte[] romFileToByteArray = ToByteArray();
             if (romFileToByteArray is null) {
                 Console.WriteLine(GetType().Name + " couldn't be saved!");
-                return;
+                return false;
             }
 
             File.WriteAllBytes(path, romFileToByteArray);
@@ -19,10 +19,12 @@ namespace DSPRE.ROMFiles {
             if (showSuccessMessage) {
                 MessageBox.Show(GetType().Name + " saved successfully!", "", MessageBoxButtons.OK, MessageBoxIcon.Information);
             }
+
+            return true;
         }
-        protected internal void SaveToFileDefaultDir(DirNames dir, int IDtoReplace, bool showSuccessMessage = true) {
+        protected internal bool SaveToFileDefaultDir(DirNames dir, int IDtoReplace, bool showSuccessMessage = true) {
             string path = RomInfo.gameDirs[dir].unpackedDir + "\\" + IDtoReplace.ToString("D4");
-            this.SaveToFile(path, showSuccessMessage);
+            return this.SaveToFile(path, showSuccessMessage);
         }
         protected internal void SaveToFileExplorePath(string fileType, string fileExtension, string suggestedFileName, bool showSuccessMessage = true) {
             fileExtension = "*." + fileExtension;

DS_Map/ROMFiles/ScriptFile.cs

@@ -700,6 +700,12 @@ namespace DSPRE.ROMFiles {
                                 AddReference(ref refList, (ushort)currentCmd.id, parameterList, (int)writer.BaseStream.Position, currentFunction);
                             }
                         } else {
+                            int functionUsescript = currentFunction.usedScript - 1;
+                            if (functionUsescript >= scriptOffsets.Count) {
+                                MessageBox.Show($"Function #{currentFunction.manualUserID} refers to Script {currentFunction.usedScript}, which does not exist.\n" +
+                                    $"This Script File can't be saved.", "Can't resolve UseScript reference", MessageBoxButtons.OK, MessageBoxIcon.Error);
+                                return null;
+                            }
                             functionOffsets.Add(new ContainerReference() {
                                 ID = currentFunction.manualUserID,
                                 offsetInFile = scriptOffsets[currentFunction.usedScript - 1].offsetInFile
@@ -749,9 +755,9 @@ namespace DSPRE.ROMFiles {
                         if (refList[i].typeOfInvoked is containerTypes.Action) { //isApplyMovement 
                             result = actionOffsets.Find(entry => entry.ID == refList[i].invokedID);
 
-                            if (result.Equals((0, 0)))
+                            if (result.Equals(default(ContainerReference))) {
                                 undeclaredActions.Add(refList[i].invokedID);
-                            else {
+                            } else {
                                 int relativeOffset = (int)(result.offsetInFile - refList[i].invokedAt - 4);
                                 writer.Write(relativeOffset);
                                 unreferencedActions.Remove(refList[i].invokedID);
@@ -759,9 +765,9 @@ namespace DSPRE.ROMFiles {
                         } else {
                             result = functionOffsets.Find(entry => entry.ID == refList[i].invokedID);
 
-                            if (result.Equals((0, 0)))
+                            if (result.Equals(default(ContainerReference))) {
                                 undeclaredFuncs.Add(refList[i].invokedID);
-                            else {
+                            } else {
                                 int relativeOffset = (int)(result.offsetInFile - refList[i].invokedAt - 4);
                                 writer.Write(relativeOffset);
 
@@ -871,8 +877,8 @@ namespace DSPRE.ROMFiles {
             return false;
         }
 
-        public void SaveToFileDefaultDir(int IDtoReplace, bool showSuccessMessage = true) {
-            SaveToFileDefaultDir(DirNames.scripts, IDtoReplace, showSuccessMessage);
+        public bool SaveToFileDefaultDir(int IDtoReplace, bool showSuccessMessage = true) {
+            return SaveToFileDefaultDir(DirNames.scripts, IDtoReplace, showSuccessMessage);
         }
         public void SaveToFileExplorePath(string suggestedFileName, bool blindmode) {
             SaveFileDialog sf = new SaveFileDialog {