라우팅 강의 내용 중 아래와 같이 에러 납니다.

    ERROR in app/app.component.html:9:3 - error NG8001: 'router-outlet' is not a known element:

    1. If 'router-outlet' is an Angular component, then verify that it is part of this module.

    2. If 'router-outlet' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.

    9   <router-outlet></router-outlet>

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

      app/app.component.ts:5:16

        5   templateUrl: './app.component.html',

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

        Error occurs in the template of component AppComponent.