Completion exceptions are never fatal.

pkg/analysis_server/lib/src/domain_completion.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 domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 39 matching lines @@
    * or `null` if none.
    */
   CompletionManager _manager;
 
   /**
    * The subscription for the cached context's source change stream.
    */
   StreamSubscription<SourcesChangedEvent> _sourcesChangedSubscription;
 
   /**
-   * Code completion peformance for the last completion operation.
+   * Code completion performance for the last completion operation.
    */
   CompletionPerformance performance;
 
   /**
-   * A list of code completion peformance measurements for the latest
+   * A list of code completion performance measurements for the latest
    * completion operation up to [performanceListMaxLength] measurements.
    */
   final List<CompletionPerformance> performanceList =
       new List<CompletionPerformance>();
 
   /**
    * Performance for the last priority change event.
    */
   CompletionPerformance computeCachePerformance;
 
@@ skipping 48 matching lines @@
   CompletionManager createCompletionManager(
       AnalysisContext context, Source source, SearchEngine searchEngine) {
     return new CompletionManager.create(context, source, searchEngine);
   }
 
   @override
   Response handleRequest(Request request) {
     if (searchEngine == null) {
       return new Response.noIndexGenerated(request);
     }
-    try {
-      String requestName = request.method;
-      if (requestName == COMPLETION_GET_SUGGESTIONS) {
-        return processRequest(request);
+    return runZoned(() {
+      try {
+        String requestName = request.method;
+        if (requestName == COMPLETION_GET_SUGGESTIONS) {
+          return processRequest(request);
+        }
+      } on RequestFailure catch (exception) {
+        return exception.response;
       }
-    } on RequestFailure catch (exception) {
-      return exception.response;
-    }
-    return null;
+      return null;
+    }, onError: (exception, stackTrace) {
+      server.sendServerErrorNotification(exception, stackTrace);
+    });
   }
 
   /**
    * If the set the priority files has changed, then pre-cache completion
    * information related to the first priority file.
    */
   void priorityChanged(PriorityChangeEvent event) {
     Source source = event.firstSource;
     CompletionPerformance performance = new CompletionPerformance();
     computeCachePerformance = performance;
@@ skipping 124 matching lines @@
     if (_sourcesChangedSubscription != null) {
       _sourcesChangedSubscription.cancel();
       _sourcesChangedSubscription = null;
     }
     if (_manager != null) {
       _manager.dispose();
       _manager = null;
     }
   }
 }