Para quem estiver com problemas na importação do ap-icon no template like-widget, basta adicionar e importar no app.module.ts o schemas: [CUSTOM_ELEMENTS_SCHEMA].
ficando assim: import { CUSTOM_ELEMENTS_SCHEMA, NgModule } from '@angular/core';
@NgModule({ declarations: [ AppComponent, LikeWidgetComponent ], imports: [ BrowserModule, AppRoutingModule ], providers: [], bootstrap: [AppComponent], schemas: [ CUSTOM_ELEMENTS_SCHEMA ] }) export class AppModule { }
