How to reopen workflow watch channel gracefully?

[zach030]

I am new with argo-workflow and confused with workflow watch Interface. I have few questions below.
1. What's the condition that leads to watch channel closed?
2. What's the proper way to reopen watch channel?

func (s *Service) WatchWorkflow() error {
	c := context.TODO()
	opts := &metav1.ListOptions{}
	watch, err := s.kc.Watch(c, *opts)
	if err != nil {
		log.Error("fail to watch %s", err.Error())
	}
	for {
		select {
		case <-c.Done():
			log.Info("ctx is done...")
			return nil
		case event, open := <-watch.ResultChan():
			if !open {
				log.Info("watch channel is closed...,event:", event)
                               // reopen watch channel
				watch, _ = s.kc.Watch(c, *opts)
			} else {
				wf, ok := event.Object.(*wfv1.Workflow)
				if !ok {
					return fmt.Errorf("error workflow format")
				}
				log.Info("watch wf: %v", wf.Name)
			}
		}
	}
}