Handle watch events that arrive before plugin start-up

pkg/analysis_server/lib/src/plugin/plugin_manager.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io' show Platform, Process, ProcessResult;
 
 import 'package:analysis_server/src/plugin/notification_manager.dart';
@@ skipping 405 matching lines @@
     bool matches(String pattern) =>
         new Glob(resourceProvider.pathContext.separator, pattern)
             .matches(filePath);
 
     WatchEvent event = null;
     List<Future<Response>> responses = <Future<Response>>[];
     for (PluginInfo plugin in _pluginMap.values) {
       PluginSession session = plugin.currentSession;
       if (session != null &&
           plugin.isAnalyzing(filePath) &&
+          session.interestingFiles != null &&
           session.interestingFiles.any(matches)) {
+        // The list of interesting file globs is `null` if the plugin has not
+        // yet responded to the plugin.versionCheck request. If that happens
+        // then the plugin hasn't had a chance to analyze anything yet, and
+        // hence it does not needed to get watch events.
         event ??= _convertWatchEvent(watchEvent);
         AnalysisHandleWatchEventsParams params =
             new AnalysisHandleWatchEventsParams([event]);
         responses.add(session.sendRequest(params));
       }
     }
     return responses;
   }
 
   /**
@@ skipping 596 matching lines @@
    * The completer that will be used to complete the future when the response is
    * received from the plugin.
    */
   final Completer<Response> completer;
 
   /**
    * Initialize a pending request.
    */
   _PendingRequest(this.method, this.requestTime, this.completer);
 }