Unwrap AsyncErrors to find real error.

utils/pub/utils.dart

Index: utils/pub/utils.dart
diff --git a/utils/pub/utils.dart b/utils/pub/utils.dart
index b922d845d4013de9e3132acb6033f3e2e5fa86b4..c3503316e85e88a954606b9e5a38ff9b84ed9fd0 100644
--- a/utils/pub/utils.dart
+++ b/utils/pub/utils.dart
@@ -183,3 +183,14 @@ void mapAddAll(Map destination, Map source) =>
 /// replacing `+` with ` `.
 String urlDecode(String encoded) =>
   decodeUriComponent(encoded.replaceAll("+", " "));
+
+/// When an error is rethrown in an async callback, you can end up with nested
+/// AsyncErrors. This unwraps them to find the real originating error.
+// TODO(rnystrom): Remove this when #7781 is fixed.

[nweiz, 2013/01/08 23:05:13]

Nit: I usually put TODOs above dartdoc comments. I think dartdoc may not pick up
on the "///" if it's below.

[Bob Nystrom, 2013/01/08 23:07:23]

Done.

+getRealError(error) {
+  while (error != null && error is AsyncError) {

[nweiz, 2013/01/08 23:05:13]

"error != null" is unnecessary here. null isn't an AsyncError.

[Bob Nystrom, 2013/01/08 23:07:23]

Done.

+    error = error.error;
+  }
+
+  return error;
+}