Source in most stuff.

dart/frog/leg/frog_leg.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('frog_leg');
 
 #import('../../lib/uri/uri.dart');
 #import('../lang.dart', prefix: 'frog');
 #import('elements/elements.dart');
 #import('io/io.dart', prefix: 'io');
@@ skipping 41 matching lines @@
     final end = node.getEndToken();
     if (begin === null || end === null) {
       cancel('cannot find tokens to produce error message for $node.');
     }
     final startOffset = begin.charOffset;
     final endOffset = end.charOffset + end.toString().length;
     return new frog.SourceSpan(current.file, startOffset, endOffset);
   }
 
   currentScript() {
+    if (currentElement === null) return null;
     CompilationUnitElement compilationUnit =
       currentElement.getCompilationUnit();
     if (compilationUnit === null) return null;
     return compilationUnit.script;
   }
 
   reportWarning(Node node, var message) {
     frog.SourceSpan span;
     Script current = currentScript();
     if (current === null) {
@@ skipping 43 matching lines @@
     }
     super.cancel(reason, node, token, instruction);
   }
 }
 
 class AbortLeg {
   final message;
   AbortLeg(this.message);
   toString() => 'Aborted due to --throw-on-error: $message';
 }