Roll Observatory deps (charted -> ^0.3.0)

packages/analyzer/lib/src/plugin/options_plugin.dart

 // Copyright (c) 2015, 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 analyzer.src.plugin.options;
 
 import 'package:analyzer/plugin/options.dart';
 import 'package:plugin/plugin.dart';
 
 /// A plugin that defines the extension points and extensions that are defined
 /// by applications that want to consume options defined in the analysis
 /// options file.
 class OptionsPlugin implements Plugin {
   /// The simple identifier of the extension point that allows plugins to
   /// register new options processors.
   static const String OPTIONS_PROCESSOR_EXTENSION_POINT = 'optionsProcessor';
 
   /// The unique identifier of this plugin.
   static const String UNIQUE_IDENTIFIER = 'options.core';
 
   /// The extension point that allows plugins to register new options processors.
   ExtensionPoint optionsProcessorExtensionPoint;
 
   /// All contributed options processors.
   List<OptionsProcessor> get optionsProcessors =>
-      optionsProcessorExtensionPoint.extensions;
+      optionsProcessorExtensionPoint == null
+          ? const []
+          : optionsProcessorExtensionPoint.extensions;
 
   @override
   String get uniqueIdentifier => UNIQUE_IDENTIFIER;
 
   @override
   void registerExtensionPoints(RegisterExtensionPoint registerExtensionPoint) {
     optionsProcessorExtensionPoint = registerExtensionPoint(
         OPTIONS_PROCESSOR_EXTENSION_POINT, _validateOptionsProcessorExtension);
   }
 
   @override
   void registerExtensions(RegisterExtension registerExtension) {
     // There are no default extensions.
   }
 
   /// Validate the given extension by throwing an [ExtensionError] if it is not a
   /// valid options processor.
   void _validateOptionsProcessorExtension(Object extension) {
     if (extension is! OptionsProcessor) {
       String id = optionsProcessorExtensionPoint.uniqueIdentifier;
       throw new ExtensionError('Extensions to $id must be an OptionsProcessor');
     }
   }
 }