fix combinator contributor

pkg/analysis_server/test/domain_completion_test.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 test.domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 340 matching lines @@
       String id = params.id;
       assertValidId(id);
       if (id == completionId) {
         expect(suggestionsDone, isFalse);
         replacementOffset = params.replacementOffset;
         replacementLength = params.replacementLength;
         suggestionsDone = params.isLast;
         expect(suggestionsDone, isNotNull);
         suggestions = params.results;
       }
+    } else if (notification.event == SERVER_ERROR) {
+      fail('server error: ${notification.toJson()}');
     }
   }
 
   @override
   void setUp() {
     super.setUp();
     createProject();
     handler = new CompletionDomainHandler(server);
   }
 
@@ skipping 473 matching lines @@
 }
     ''');
     await waitForTasksFinished();
     Request request =
         new CompletionGetSuggestionsParams(testFile, 0).toRequest('0');
     Response response = handler.handleRequest(request);
     expect(response.error, isNotNull);
     expect(response.error.code, RequestErrorCode.NO_INDEX_GENERATED);
   }
 }