possible workaround to SD2-941.

i couldn't reproduce the problem illustrated in SD2-941, but instead this addresses the crash when BooBinding tries to reference FormsDesigner if the FormsDesigner.addin file does not exist.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@1593 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Main/Core/Project/Src/Services/MessageService/MessageService.cs

@@ -81,6 +81,13 @@ namespace ICSharpCode.Core
 				msg += "Exception occurred: " + ex.ToString();
 			}
 			
+			if (MessageService.MainForm == null) {
+				// let's try this; don't know if it's threadsafe?  I expect
+				// that MainForm.InvokeRequired can be assumed to be false
+				// if MainForm doesn't exist yet...
+				MessageBox.Show(StringParser.Parse(msg), StringParser.Parse("SharpDevelop: ${res:Global.ErrorText}"), MessageBoxButtons.OK, MessageBoxIcon.Error);			
+			} else {
+			
 			MethodInvoker showError = delegate {
 				MessageBox.Show(MessageService.MainForm, StringParser.Parse(msg), StringParser.Parse("${res:Global.ErrorText}"), MessageBoxButtons.OK, MessageBoxIcon.Error);
 			};
@@ -89,6 +96,7 @@ namespace ICSharpCode.Core
 			} else {
 				showError();
 			}
+			}
 		}
 		
 		public static void ShowWarning(string message)