Issue 27542. Guard against CompilationUnitElement is null in SearchMatch.element getter.

pkg/analysis_server/lib/src/search/search_domain.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 search.domain;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
@@ skipping 80 matching lines @@
     var params =
         new protocol.SearchFindMemberDeclarationsParams.fromRequest(request);
     await server.onAnalysisComplete;
     // respond
     String searchId = (_nextSearchId++).toString();
     _sendSearchResult(
         request, new protocol.SearchFindMemberDeclarationsResult(searchId));
     // search
     List<SearchMatch> matches =
         await searchEngine.searchMemberDeclarations(params.name);
+    matches = SearchMatch.withNotNullElement(matches);
     _sendSearchNotification(searchId, true, matches.map(toResult));
   }
 
   Future findMemberReferences(protocol.Request request) async {
     var params =
         new protocol.SearchFindMemberReferencesParams.fromRequest(request);
     await server.onAnalysisComplete;
     // respond
     String searchId = (_nextSearchId++).toString();
     _sendSearchResult(
         request, new protocol.SearchFindMemberReferencesResult(searchId));
     // search
     List<SearchMatch> matches =
         await searchEngine.searchMemberReferences(params.name);
+    matches = SearchMatch.withNotNullElement(matches);
     _sendSearchNotification(searchId, true, matches.map(toResult));
   }
 
   Future findTopLevelDeclarations(protocol.Request request) async {
     var params =
         new protocol.SearchFindTopLevelDeclarationsParams.fromRequest(request);
     try {
       // validate the regex
       new RegExp(params.pattern);
     } on FormatException catch (exception) {
       server.sendResponse(new protocol.Response.invalidParameter(
           request, 'pattern', exception.message));
       return;
     }
 
     await server.onAnalysisComplete;
     // respond
     String searchId = (_nextSearchId++).toString();
     _sendSearchResult(
         request, new protocol.SearchFindTopLevelDeclarationsResult(searchId));
     // search
     List<SearchMatch> matches =
         await searchEngine.searchTopLevelDeclarations(params.pattern);
+    matches = SearchMatch.withNotNullElement(matches);
     _sendSearchNotification(searchId, true, matches.map(toResult));
   }
 
   /**
    * Implement the `search.getTypeHierarchy` request.
    */
   Future getTypeHierarchy(protocol.Request request) async {
     var params = new protocol.SearchGetTypeHierarchyParams.fromRequest(request);
     String file = params.file;
     // wait for analysis
@@ skipping 77 matching lines @@
   void _sendTypeHierarchyNull(protocol.Request request) {
     protocol.Response response =
         new protocol.SearchGetTypeHierarchyResult().toResponse(request.id);
     server.sendResponse(response);
   }
 
   static protocol.SearchResult toResult(SearchMatch match) {
     return protocol.newSearchResult_fromMatch(match);
   }
 }