Remove AsyncError with Expando.

utils/pub/command_uploader.dart

 // Copyright (c) 2012, 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 command_uploader;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:uri';
 
@@ skipping 58 matching lines @@
         if (command == 'add') {
           var url = server.resolve("/packages/${encodeUriComponent(package)}"
               "/uploaders.json");
           return client.post(url, fields: {"email": uploader});
         } else { // command == 'remove'
           var url = server.resolve("/packages/${encodeUriComponent(package)}"
               "/uploaders/${encodeUriComponent(uploader)}.json");
           return client.delete(url);
         }
       });
-    }).then(handleJsonSuccess).catchError((asyncError) {
-      if (asyncError.error is! PubHttpException) throw asyncError;
-      handleJsonError(asyncError.error.response);
-    });
+    }).then(handleJsonSuccess)
+      .catchError((error) => handleJsonError(error.response),
+                  test: (e) => e is PubHttpException);
   }
 }