Fix type cast problems now that watch can pass errors

pkg/registry/controller/rest.go

@@ -150,8 +150,14 @@ func (rs *REST) Watch(label, field labels.Selector, resourceVersion uint64) (wat
 	if err != nil {
 		return nil, err
 	}
+	// TODO(lavalamp): remove watch.Filter, which is broken. Implement consistent way of filtering.
+	// TODO(lavalamp): this watch method needs a test.
 	return watch.Filter(incoming, func(e watch.Event) (watch.Event, bool) {
-		repController := e.Object.(*api.ReplicationController)
+		repController, ok := e.Object.(*api.ReplicationController)
+		if !ok {
+			// must be an error event-- pass it on
+			return e, true
+		}
 		match := label.Matches(labels.Set(repController.Labels))
 		if match {
 			rs.fillCurrentState(repController)

pkg/registry/etcd/etcd.go

@@ -85,12 +85,13 @@ func (r *Registry) ListPodsPredicate(filter func(*api.Pod) bool) (*api.PodList,
 // WatchPods begins watching for new, changed, or deleted pods.
 func (r *Registry) WatchPods(resourceVersion uint64, filter func(*api.Pod) bool) (watch.Interface, error) {
 	return r.WatchList("/registry/pods", resourceVersion, func(obj runtime.Object) bool {
-		pod, ok := obj.(*api.Pod)
-		if !ok {
-			glog.Errorf("Unexpected object during pod watch: %#v", obj)
-			return false
+		switch t := obj.(type) {
+		case *api.Pod:
+			return filter(t)
+		default:
+			// Must be an error
+			return true
 		}
-		return filter(pod)
 	})
 }