Again, we have to register the new component within the app.module.shared.ts file:

[...]

import { LoginFacebookComponent } from './components/login/login.facebook.component';
import { LoginExternalProvidersComponent } from './components/login/login.externalproviders.component';

@NgModule({
    declarations: [

[...]

        LoginFacebookComponent,
        LoginExternalProvidersComponent,

[...]