Create a NullErrorReporter to use when errors don't need to be recorded.

pkg/analyzer/lib/src/generated/error.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.error;
 
 import 'dart:collection';
@@ skipping 2757 matching lines @@
   ErrorSeverity get errorSeverity => ErrorSeverity.WARNING;
 
   @override
   ErrorType get type => ErrorType.STATIC_WARNING;
 
   @override
   String get uniqueName => "${runtimeType.toString()}.${name}";
 }
 
 /**
+ * Instances of the class `NullErrorListener` implement the
+ * AnalysisErrorListener interface, but don't record any information.
+ */
+class NullErrorListener implements AnalysisErrorListener {

[Brian Wilkerson, 2014/10/06 16:49:41]

Or use the poorly named but existing class
AnalysisErrorListener_NULL_LISTENER...

[Paul Berry, 2014/10/06 16:56:52]

Done.

+  @override
+  void onError(AnalysisError error) {
+  }
+}
+
+/**
  * The enumeration `PolymerCode` defines Polymer specific problems.
  */
 class PolymerCode extends Enum<PolymerCode> implements ErrorCode {
   static const PolymerCode ATTRIBUTE_FIELD_NOT_PUBLISHED = const PolymerCode('ATTRIBUTE_FIELD_NOT_PUBLISHED', 0, "Field '{0}' in '{1}' must be @published");
 
   static const PolymerCode DUPLICATE_ATTRIBUTE_DEFINITION = const PolymerCode('DUPLICATE_ATTRIBUTE_DEFINITION', 1, "The attribute '{0}' is already defined");
 
   static const PolymerCode EMPTY_ATTRIBUTES = const PolymerCode('EMPTY_ATTRIBUTES', 2, "Empty 'attributes' attribute is useless");
 
   static const PolymerCode INVALID_ATTRIBUTE_NAME = const PolymerCode('INVALID_ATTRIBUTE_NAME', 3, "'{0}' is not a valid name for a custom element attribute");
@@ skipping 1436 matching lines @@
 
   @override
   String get message => "{0}";
 
   @override
   ErrorType get type => ErrorType.TODO;
 
   @override
   String get uniqueName => "${runtimeType.toString()}.${name}";
 }