| Index: pkg/polymer/lib/src/build/runner.dart
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| diff --git a/pkg/polymer/lib/src/build/runner.dart b/pkg/polymer/lib/src/build/runner.dart
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| index b59b1b8d814cb5c13b8e48fe02e4bc437fd183c9..c7658deb8ae20ba20fa6a2232092cec9842fa8e2 100644
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| --- a/pkg/polymer/lib/src/build/runner.dart
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| +++ b/pkg/polymer/lib/src/build/runner.dart
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| @@ -174,7 +174,8 @@ void _initBarback(Barback barback, BarbackOptions options) {
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|  void _attachListeners(Barback barback) {
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|    // Listen for errors and results
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|    barback.errors.listen((e) {
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| -    var trace = getAttachedStackTrace(e);
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| +    var trace = null;
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| +    if (e is Error) trace = e.stackTrace;
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|      if (trace != null) {
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|        print(Trace.format(trace));
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|      }
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| 
 |