Issue 23573. Catch exception during indexing.

pkg/analysis_server/lib/src/operation/operation_analysis.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 operation.analysis;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/computer/computer_highlights.dart';
 import 'package:analysis_server/src/computer/computer_navigation.dart';
 import 'package:analysis_server/src/computer/computer_occurrences.dart';
@@ skipping 308 matching lines @@
       : super(context, file);
 
   @override
   ServerOperationPriority get priority {
     return ServerOperationPriority.ANALYSIS_INDEX;
   }
 
   @override
   void perform(AnalysisServer server) {
     ServerPerformanceStatistics.indexOperation.makeCurrentWhile(() {
-      Index index = server.index;
-      index.indexUnit(context, unit);
+      try {
+        Index index = server.index;
+        index.indexUnit(context, unit);
+      } catch (exception, stackTrace) {
+        server.sendServerErrorNotification(exception, stackTrace);
+      }
     });
   }
 }
 
 class _DartNavigationOperation extends _DartNotificationOperation {
   _DartNavigationOperation(
       AnalysisContext context, String file, CompilationUnit unit)
       : super(context, file, unit);
 
   @override
@@ skipping 89 matching lines @@
 abstract class _SingleFileOperation extends SourceSensitiveOperation {
   final String file;
 
   _SingleFileOperation(AnalysisContext context, this.file) : super(context);
 
   @override
   bool shouldBeDiscardedOnSourceChange(Source source) {
     return source.fullName == file;
   }
 }