#1481: Improve exception handling in case of MEF initialization errors.

ILSpy/App.xaml.cs

@@ -32,6 +32,7 @@ using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.Options;
 
 using Microsoft.VisualStudio.Composition;
+using System.Text;
 
 namespace ICSharpCode.ILSpy
 {
@@ -71,7 +72,13 @@ namespace ICSharpCode.ILSpy
 				}
 			}
 			InitializeComponent();
-			
+
+			if (!System.Diagnostics.Debugger.IsAttached) {
+				AppDomain.CurrentDomain.UnhandledException += ShowErrorBox;
+				Dispatcher.CurrentDispatcher.UnhandledException += Dispatcher_UnhandledException;
+			}
+			TaskScheduler.UnobservedTaskException += DotNet40_UnobservedTaskException;
+
 			// Cannot show MessageBox here, because WPF would crash with a XamlParseException
 			// Remember and show exceptions in text output, once MainWindow is properly initialized
 			try {
@@ -107,16 +114,10 @@ namespace ICSharpCode.ILSpy
 				// This throws exceptions for composition failures. Alternatively, the configuration's CompositionErrors property
 				// could be used to log the errors directly. Used at the end so that it does not prevent the export provider setup.
 				config.ThrowOnErrors();
-			}
-			catch (Exception ex) {
+			} catch (Exception ex) {
 				StartupExceptions.Add(new ExceptionData { Exception = ex });
 			}
 			
-			if (!System.Diagnostics.Debugger.IsAttached) {
-				AppDomain.CurrentDomain.UnhandledException += ShowErrorBox;
-				Dispatcher.CurrentDispatcher.UnhandledException += Dispatcher_UnhandledException;
-			}
-			TaskScheduler.UnobservedTaskException += DotNet40_UnobservedTaskException;
 			Languages.Initialize(exportProvider);
 
 			EventManager.RegisterClassHandler(typeof(Window),
@@ -124,7 +125,17 @@ namespace ICSharpCode.ILSpy
 			                                  new RequestNavigateEventHandler(Window_RequestNavigate));
 			ILSpyTraceListener.Install();
 		}
-		
+
+		protected override void OnStartup(StartupEventArgs e)
+		{
+			var output = new StringBuilder();
+			if (ILSpy.MainWindow.FormatExceptions(StartupExceptions.ToArray(), output)) {
+				MessageBox.Show(output.ToString(), "Sorry we crashed!");
+				Environment.Exit(1);
+			}
+			base.OnStartup(e);
+		}
+
 		string FullyQualifyPath(string argument)
 		{
 			// Fully qualify the paths before passing them to another process,

ILSpy/MainWindow.xaml.cs

@@ -24,6 +24,7 @@ using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Reflection.Metadata;
+using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
@@ -451,6 +452,16 @@ namespace ICSharpCode.ILSpy
 		}
 		
 		bool FormatExceptions(App.ExceptionData[] exceptions, ITextOutput output)
+		{
+			var stringBuilder = new StringBuilder();
+			var result = FormatExceptions(exceptions, stringBuilder);
+			if (result) {
+				output.Write(stringBuilder.ToString());
+			}
+			return result;
+		}
+
+		internal static bool FormatExceptions(App.ExceptionData[] exceptions, StringBuilder output)
 		{
 			if (exceptions.Length == 0) return false;
 			bool first = true;
@@ -459,16 +470,16 @@ namespace ICSharpCode.ILSpy
 				if (first)
 					first = false;
 				else
-					output.WriteLine("-------------------------------------------------");
-				output.WriteLine("Error(s) loading plugin: " + item.PluginName);
+					output.AppendLine("-------------------------------------------------");
+				output.AppendLine("Error(s) loading plugin: " + item.PluginName);
 				if (item.Exception is System.Reflection.ReflectionTypeLoadException) {
 					var e = (System.Reflection.ReflectionTypeLoadException)item.Exception;
 					foreach (var ex in e.LoaderExceptions) {
-						output.WriteLine(ex.ToString());
-						output.WriteLine();
+						output.AppendLine(ex.ToString());
+						output.AppendLine();
 					}
 				} else
-					output.WriteLine(item.Exception.ToString());
+					output.AppendLine(item.Exception.ToString());
 			}
 			
 			return true;