Report an error on Dart Source reading exception.

pkg/analyzer/lib/src/generated/scanner.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 engine.scanner;
 
 import 'dart:collection';
 
 import 'error.dart';
 import 'java_engine.dart';
@@ skipping 1798 matching lines @@
 
   static const ScannerErrorCode MISSING_DIGIT =
       const ScannerErrorCode('MISSING_DIGIT', "Decimal digit expected");
 
   static const ScannerErrorCode MISSING_HEX_DIGIT =
       const ScannerErrorCode('MISSING_HEX_DIGIT', "Hexidecimal digit expected");
 
   static const ScannerErrorCode MISSING_QUOTE =
       const ScannerErrorCode('MISSING_QUOTE', "Expected quote (' or \")");
 
+  static const ScannerErrorCode UNABLE_GET_CONTENT =
+      const ScannerErrorCode('UNABLE_GET_CONTENT', "Unable to get content");
+
   static const ScannerErrorCode UNTERMINATED_MULTI_LINE_COMMENT =
       const ScannerErrorCode(
           'UNTERMINATED_MULTI_LINE_COMMENT',
           "Unterminated multi-line comment");
 
   static const ScannerErrorCode UNTERMINATED_STRING_LITERAL =
       const ScannerErrorCode(
           'UNTERMINATED_STRING_LITERAL',
           "Unterminated string literal");
 
@@ skipping 808 matching lines @@
   CommentToken get precedingComments => _precedingComment;
 
   void set precedingComments(CommentToken comment) {
     _precedingComment = comment;
     _setCommentParent(_precedingComment);
   }
 
   @override
   Token copy() => new TokenWithComment(type, offset, precedingComments);
 }