case v := <-updateCloser:
				update()
				xioutil.SafeClose(v)
				return
			case <-updateTicker.C:
				update()
			}
		}
	}()

	wg.Wait()
	ch := make(chan struct{})
	select {
	case updateCloser <- ch:
		<-ch
	case <-ctx.Done():
		mu.Lock()
		if firstErr == nil {
			firstErr = ctx.Err()
		}
		defer mu.Unlock()
	}
	return firstErr
}