Consider a thrown AsyncError from a future/stream handler a rethrow.

tests/lib/async/future_test.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 future_test;
 
 import 'dart:async';
 import 'dart:isolate';
 
 testImmediate() {
@@ skipping 425 matching lines @@
   }).then((v) {
     Expect.fail("should fail async");
   }, onError: (AsyncError e) {
     Expect.equals("Fail", e.error);
     countDown(1);
   });
 
   completer.completeError("Error");
 }
 
+testFutureThenThrowsAsync() {
+  final completer = new Completer<int>();
+  final future = completer.future;
+  AsyncError error = new AsyncError(42, "st");
 
+  var port = new ReceivePort();
+  future.then((v) {
+    throw error;
+  }).catchError((AsyncError e) {
+    Expect.identical(error, e);
+    port.close();
+  });
+  completer.complete(0);
+}
+
+testFutureCatchThrowsAsync() {
+  final completer = new Completer<int>();
+  final future = completer.future;
+  AsyncError error = new AsyncError(42, "st");
+
+  var port = new ReceivePort();
+  future.catchError((AsyncError e) {
+    throw error;
+  }).catchError((AsyncError e) {
+    Expect.identical(error, e);
+    port.close();
+  });
+  completer.completeError(0);
+}
+
+testFutureCatchRethrowsAsync() {
+  final completer = new Completer<int>();
+  final future = completer.future;
+  AsyncError error;
+
+  var port = new ReceivePort();
+  future.catchError((AsyncError e) {
+    error = e;
+    throw e;
+  }).catchError((AsyncError e) {
+    Expect.identical(error, e);
+    port.close();
+  });
+  completer.completeError(0);
+}
+
+testFutureWhenThrowsAsync() {
+  final completer = new Completer<int>();
+  final future = completer.future;
+  AsyncError error = new AsyncError(42, "st");
+
+  var port = new ReceivePort();
+  future.whenComplete(() {
+    throw error;
+  }).catchError((AsyncError e) {
+    Expect.identical(error, e);
+    port.close();
+  });
+  completer.complete(0);
+}
+
+testCompleteWithAsyncError() {
+  final completer = new Completer<int>();
+  final future = completer.future;
+  AsyncError error = new AsyncError(42, "st");
+
+  var port = new ReceivePort();
+  future.catchError((AsyncError e) {
+    Expect.identical(error, e);
+    port.close();
+  });
+
+  completer.completeError(error);
+}
 
 main() {
   testImmediate();
   testNeverComplete();
 
   testComplete();
   testCompleteWithSuccessHandlerBeforeComplete();
   testCompleteWithSuccessHandlerAfterComplete();
   testCompleteManySuccessHandlers();
+  testCompleteWithAsyncError();
 
   testException();
   testExceptionHandler();
   testExceptionHandlerReturnsTrue();
   testExceptionHandlerReturnsTrue2();
   testExceptionHandlerReturnsFalse();
 
   testFutureAsStreamCompleteAfter();
   testFutureAsStreamCompleteBefore();
   testFutureAsStreamCompleteImmediate();
   testFutureAsStreamCompleteErrorAfter();
   testFutureAsStreamWrapper();
 
   testFutureWhenCompleteValue();
   testFutureWhenCompleteError();
   testFutureWhenCompleteValueNewError();
   testFutureWhenCompleteErrorNewError();
 
   testFutureWhenValueFutureValue();
   testFutureWhenErrorFutureValue();
   testFutureWhenValueFutureError();
   testFutureWhenErrorFutureError();
+
+  testFutureThenThrowsAsync();
+  testFutureCatchThrowsAsync();
+  testFutureWhenThrowsAsync();
+  testFutureCatchRethrowsAsync();
 }