I had this function running in TypeScript, when I tried to call a base class constructor with "super". 

  constructor(
    public http: HttpClient,
    public router: Router,
  ) {
    super(http);
    super(router);

    this.currentUserSubject = new BehaviorSubject<User | null>(null);
  }

Solution

The solution was to add them both to the first super() call:

  constructor(
    public http: HttpClient,
    public router: Router,
  ) {
    super(http, router);

    this.currentUserSubject = new BehaviorSubject<User | null>(null);
  }