错误消息：

src/app/ngrxdemo/container/component/counter/counter.component.html:8:27 - error NG8004: No pipe found with name ‘async’.

8 当前数：{undefined{ counter$ | async }}

~~~~~

src/app/ngrxdemo/container/component/counter/counter.component.ts:9:16

9 templateUrl: ‘./counter.component.html’,

~~~~~~~~~~~~~~~~~~~~~~~~~~

Error occurs in the template of component CounterComponent.

虽然CounterComponent作为child Component，其parent Component里已经申明了包含async pipe的Common Module，但是仍然需要在child Component里也import Common Module：

import之后问题解决：