Add rough error logging

#727

NHSE.WinForms/Program.cs

@@ -2,6 +2,11 @@
 using System.IO;
 using System.Windows.Forms;
 
+#if !DEBUG
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+#endif
+
 namespace NHSE.WinForms;
 
 internal static class Program
@@ -31,6 +36,11 @@ internal static class Program
     /// </summary>
     static Program()
     {
+#if !DEBUG
+        Application.ThreadException += UIThreadException;
+        Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
+        AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
+#endif
         Application.EnableVisualStyles();
         Application.SetCompatibleTextRenderingDefault(false);
         Settings = ApplicationSettings.Load(PathConfig);
@@ -44,4 +54,105 @@ static Program()
     private static void Main() => Application.Run(new Main());
 
     public static void SaveSettings() => Settings.Save(PathConfig);
+
+
+#if !DEBUG
+    private static void Error(string msg) => MessageBox.Show(msg, "NHSE Error", MessageBoxButtons.OK, MessageBoxIcon.Stop);
+
+    private static void UIThreadException(object sender, ThreadExceptionEventArgs t)
+    {
+        DialogResult result;
+        try
+        {
+            var e = t.Exception;
+            string errorMessage = GetErrorMessage(e);
+            Error(errorMessage);
+            result = DialogResult.OK;
+        }
+        catch (Exception reportingException)
+        {
+            HandleReportingException(t.Exception, reportingException);
+            result = DialogResult.Abort;
+        }
+
+        if (result == DialogResult.Abort)
+            Application.Exit();
+    }
+
+    private static string GetErrorMessage(Exception e)
+    {
+        Console.WriteLine(e);
+        return e.StackTrace ?? e.Message;
+    }
+
+    private static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
+    {
+        var ex = e.ExceptionObject as Exception;
+        try
+        {
+            if (IsCoreMissing(ex))
+            {
+                Error("You have installed NHSE incorrectly. Please ensure you have unzipped all files before running.");
+            }
+            else if (ex is not null)
+            {
+                Error(GetErrorMessage(ex));
+            }
+            else
+            {
+                Error("A fatal non-UI error has occurred in NHSE, and the details could not be displayed.  Please report this to the author.");
+            }
+        }
+        catch (Exception reportingException)
+        {
+            HandleReportingException(ex, reportingException);
+        }
+    }
+
+    private static void HandleReportingException(Exception? ex, Exception reportingException)
+    {
+        try
+        {
+            EmergencyErrorLog(ex, reportingException);
+        }
+        catch
+        {
+            // Ignore.
+        }
+        if (reportingException is FileNotFoundException x && x.FileName?.StartsWith("NHSE.Core") == true)
+        {
+            Error("Could not locate NHSE.Core.dll. Make sure you're running NHSE together with its code library. Usually caused when all files are not extracted.");
+            return;
+        }
+        try
+        {
+            Error("A fatal non-UI error has occurred in NHSE, and there was a problem displaying the details.  Please report this to the author.");
+        }
+        finally
+        {
+            Application.Exit();
+        }
+    }
+
+    private static bool EmergencyErrorLog(Exception? originalException, Exception errorHandlingException)
+    {
+        try
+        {
+            var message = (originalException?.ToString() ?? "null first exception") + Environment.NewLine + errorHandlingException;
+            File.WriteAllText($"NHSE_Error_Report {DateTime.Now:yyyyMMddHHmmss}.txt", message);
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine(errorHandlingException);
+            Console.WriteLine(ex);
+            return false;
+        }
+        return true;
+    }
+
+    private static bool IsCoreMissing([NotNullWhen(true)] Exception? ex)
+    {
+        return ex is FileNotFoundException { FileName: { } n } && n.Contains("NHSE.Core");
+    }
+#endif
 }