Guard against null pointer exception in status page generation

pkg/analysis_server/lib/src/status/get_handler.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.src.status.get_handler;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 359 matching lines @@
   }
 
   /**
    * Return `true` if the given analysis [context] has at least one entry with
    * an exception.
    */
   bool _hasException(InternalAnalysisContext context) {
     MapIterator<AnalysisTarget, CacheEntry> iterator =
         context.analysisCache.iterator();
     while (iterator.moveNext()) {
-      if (iterator.value.exception != null) {
+      CacheEntry entry = iterator.value;
+      if (entry != null && entry.exception != null) {

[scheglov, 2015/11/11 22:46:12]

Should we log / write-to-the-page the key for which we were not able to get the
entry?

         return true;
       }
     }
     return false;
   }
 
   /**
    * Return the folder in the [folderMap] with which the given [context] is
    * associated.
    */
@@ skipping 1545 matching lines @@
    */
   static String makeLink(
       String path, Map<String, String> params, String innerHtml,
       [bool hasError = false]) {
     Uri uri = new Uri(path: path, queryParameters: params);
     String href = HTML_ESCAPE.convert(uri.toString());
     String classAttribute = hasError ? ' class="error"' : '';
     return '<a href="$href"$classAttribute>$innerHtml</a>';
   }
 }