Don't propagate synchronous Future.wait errors immediately.

sdk/lib/async/future.dart

Index: sdk/lib/async/future.dart
diff --git a/sdk/lib/async/future.dart b/sdk/lib/async/future.dart
index c64e1c5e0316ca6baa5997c9eb131f6b768bb9bd..ff646e0e9e4cd716a1fa0f89c4f6c2233724f836 100644
--- a/sdk/lib/async/future.dart
+++ b/sdk/lib/async/future.dart
@@ -322,8 +322,11 @@ abstract class Future<T> {
       // The error must have been thrown while iterating over the futures
       // list, or while installing a callback handler on the future.
       if (remaining == 0 || eagerError) {
-        // Just complete the error immediately.
-        result._completeError(e, st);
+        // Throw a new Future.error.
+        // Don't just complete the existing `_Future` since that would propagate

[Lasse Reichstein Nielsen, 2016/09/06 09:53:27]

Drop this comment. If you used _asyncCompleteError it wouldn't be a problem. Say
that this also gives the zone a chance to intercept the error.

[floitsch, 2016/09/06 09:57:15]

Done.

+        // the error too eagerly, not giving the callers time to install
+        // error handlers.
+        return new Future.error(e, st);
       } else {
         // Don't allocate a list for values, thus indicating that there was an
         // error.