guard against non-existant package directory

pkg/analysis_server/lib/src/context_manager.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 context.directory.manager;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 377 matching lines @@
    */
   UriResolver _computePackageUriResolver(Folder folder, _ContextInfo info) {
     if (info.packageRoot != null) {
       info.packageMapInfo = null;
       JavaFile packagesDir = new JavaFile(info.packageRoot);
       Map<String, List<Folder>> packageMap = new Map<String, List<Folder>>();
       if (packagesDir.isDirectory()) {
         for (JavaFile file in packagesDir.listFiles()) {
           // Ensure symlinks in packages directory are canonicalized
           // to prevent 'type X cannot be assigned to type X' warnings
-          Resource res = resourceProvider.getResource(file.getCanonicalPath());
+          String path;
+          try {
+            path = file.getCanonicalPath();
+          } catch (e, s) {
+            // Ignore packages that do not exist
+            _instrumentationService.logException(e, s);
+            continue;
+          }
+          Resource res = resourceProvider.getResource(path);

[Brian Wilkerson, 2015/04/24 21:43:20]

Consider moving the four lines after the try-catch into the try block. It will
allow you to declare the variable in the try block as well as drop the continue.

           if (res is Folder) {
             packageMap[file.getName()] = <Folder>[res];
           }
         }
         return new PackageMapUriResolver(resourceProvider, packageMap);
       }
       //TODO(danrubel) remove this if it will never be called
       return new PackageUriResolver([packagesDir]);
     } else {
       beginComputePackageMap();
@@ skipping 385 matching lines @@
     return excludes(resource.path);
   }
 
   /**
    * Returns `true` if [path] is the pubspec file of this context.
    */
   bool isPubspec(String path) {
     return path == pubspecPath;
   }
 }