Don't use firstWhere as it throws an error if there is no such element

pkg/analyzer/lib/src/generated/source.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.source;
 
 import "dart:math" as math;
@@ skipping 587 matching lines @@
    *
    * @param localSourcePredicate the predicate to determine is [Source] is local
    */
   void set localSourcePredicate(LocalSourcePredicate localSourcePredicate) {
     this._localSourcePredicate = localSourcePredicate;
   }
 
   /// A table mapping package names to paths of directories containing
   /// the package (or [null] if there is no registered package URI resolver).
   Map<String, List<Folder>> get packageMap {
-    PackageMapUriResolver resolver =
-        _resolvers.firstWhere((r) => r is PackageMapUriResolver, orElse: null);

[Paul Berry, 2015/02/02 23:15:25]

Nit: why not just use:

orElse: () => null

[pquitslund, 2015/02/02 23:19:39]

This! :)

-    return resolver != null ? resolver.packageMap : null;
+    for(UriResolver r in _resolvers) {
+      if(r is PackageMapUriResolver) {

[pquitslund, 2015/02/02 23:19:12]

Run the formatter?  The should (at least) be a space between if(r ...

+        return r.packageMap;
+      }
+    }
+    return null;
   }
 
   /**
    * Return a source object representing the given absolute URI, or `null` if the URI is not a
    * valid URI or if it is not an absolute URI.
    *
    * @param absoluteUri the absolute URI to be resolved
    * @return a source object representing the absolute URI
    */
   Source forUri(String absoluteUri) {
@@ skipping 363 matching lines @@
 
   /**
    * Return an absolute URI that represents the given source, or `null` if a valid URI cannot
    * be computed.
    *
    * @param source the source to get URI for
    * @return the absolute URI representing the given source
    */
   Uri restoreAbsolute(Source source) => null;
 }