Fix for an error in the error handler.

pkg/analysis_server/lib/src/analysis_server.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/file_system/file_system.dart';
@@ skipping 417 matching lines @@
             return;
           }
           if (response != null) {
             channel.sendResponse(response);
             return;
           }
         } on RequestFailure catch (exception) {
           channel.sendResponse(exception.response);
           return;
         } catch (exception, stackTrace) {
-          RequestError error =
-              new RequestError(RequestErrorCode.SERVER_ERROR, exception);
+          RequestError error = new RequestError(
+              RequestErrorCode.SERVER_ERROR,
+              exception.toString());
           if (stackTrace != null) {
             error.stackTrace = stackTrace.toString();
           }
           Response response = new Response(request.id, error: error);
           channel.sendResponse(response);
           return;
         }
       }
       channel.sendResponse(new Response.unknownRequest(request));
     }, onError: _sendServerErrorNotification);
@@ skipping 495 matching lines @@
     // send the notification
     channel.sendNotification(
         new ServerErrorParams(
             true,
             exceptionString,
             stackTraceString).toNotification());
   }
 }
 
 typedef void OptionUpdater(AnalysisOptionsImpl options);