Fix #561: Clicking on a node with a deleted file causes a stacktrace to be printed instead of a user friendly "File doesn't exist" message

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -251,14 +251,28 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
+			void HandleException(Exception ex, string message)
+			{
+				language.WriteCommentLine(output, message);
+
+				output.WriteLine();
+				output.MarkFoldStart("Exception details", true);
+				output.Write(ex.ToString());
+				output.MarkFoldEnd();
+			}
+
 			try {
 				assembly.WaitUntilLoaded(); // necessary so that load errors are passed on to the caller
 			} catch (AggregateException ex) {
 				language.WriteCommentLine(output, assembly.FileName);
-				if (ex.InnerException is BadImageFormatException) {
-					language.WriteCommentLine(output, "This file does not contain a managed assembly.");
+				switch (ex.InnerException) {
+					case BadImageFormatException badImage:
+						HandleException(badImage, "This file does not contain a managed assembly.");
 						return;
-				} else {
+					case FileNotFoundException fileNotFound:
+						HandleException(fileNotFound, "The file was not found.");
+						return;
+					default:
 						throw;
 				}
 			}