cambio la definicion de app.component.ts

app.component.ts

export class AppComponent{
  user: User;
  isLoggingIn = true;

  constructor(){
    this.user = new User();
  }
  submit():void{
    alert("esta el mail: " + this.user.email);
  }
  toggleDisplay(){
    this.isLoggingIn = !this.isLoggingIn;
  }
}