Remove AsyncError with Expando.

pkg/scheduled_test/lib/src/descriptor/pattern_descriptor.dart

 // Copyright (c) 2013, 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 descriptor.pattern;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:pathos/path.dart' as path;
@@ skipping 44 matching lines @@
     matchingEntries.sort();
 
     if (matchingEntries.isEmpty) {
       throw "No entry found in '$parent' matching ${_patternDescription}.";
     }
 
     return Future.wait(matchingEntries.map((entry) {
       var descriptor = _fn(path.basename(entry));
       return descriptor.validateNow(parent).then((_) {
         return new Pair(null, descriptor.describe());
-      }).catchError((e) {
-        return new Pair(e.error.toString(), descriptor.describe());
+      }).catchError((error) {
+        return new Pair(error.toString(), descriptor.describe());
       });
     })).then((results) {
       var matches = results.where((result) => result.first == null).toList();
       // If exactly one entry matching [pattern] validated, we're happy.
       if (matches.length == 1) return;
 
       // If more than one entry matching [pattern] validated, that's bad.
       if (matches.length > 1) {
         var resultString = matches.map((result) {
           return prefixLines(result.last, firstPrefix: '* ', prefix: '  ');
@@ skipping 35 matching lines @@
 
   Future create([String parent]) => new Future.immediateError(
       new UnsupportedError("Pattern descriptors don't support create()."));
 
   Stream<List<int>> load(String pathToLoad) => errorStream(
       new UnsupportedError("Pattern descriptors don't support load()."));
 
   Stream<List<int>> read() => errorStream(new UnsupportedError("Pattern "
       "descriptors don't support read()."));
 }