pkg/scheduled_test: handle null currentSchedule due to timeout

pkg/scheduled_test/test/scheduled_test/current_schedule_errors_test.dart

Index: pkg/scheduled_test/test/scheduled_test/current_schedule_errors_test.dart
diff --git a/pkg/scheduled_test/test/scheduled_test/current_schedule_errors_test.dart b/pkg/scheduled_test/test/scheduled_test/current_schedule_errors_test.dart
index 048745ddbea01962ea143e10181ebf1d7e6832d9..749ec6e5e841330e587fb12e5d4c3de599289581 100644
--- a/pkg/scheduled_test/test/scheduled_test/current_schedule_errors_test.dart
+++ b/pkg/scheduled_test/test/scheduled_test/current_schedule_errors_test.dart
@@ -2,6 +2,8 @@
 // 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.
 
+import 'dart:async';
+
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/src/mock_clock.dart' as mock_clock;
 
@@ -13,6 +15,16 @@ void main(_, message) {
 
   setUpTimeout();
 
+  expectTests('a scheduled test with an out-of-band error should fail', () {
+    test('test 1', () {
+      sleep(5).then((_) => throw 'error');

[nweiz, 2014/04/10 00:58:15]

If you're going to use [sleep] like this, you need to call
`mock_clock.mock().run()` at the beginning of the block.

Also, there's no reason to sleep for 5 and 10 increments; just 1 and 2 will do.
Each increment corresponds to a full [pumpEventQueue] iteration.

+    });
+
+    test('test 2', () {
+      return sleep(10);
+    });
+  }, {'test 1': ERROR, 'test 2': PASS});
+
   expectTestsPass('currentSchedule.errors contains the error in the onComplete '
       'queue', () {
     var errors;