TypeError: You provided 'undefined' where a stream was expected

Question

I have an Ionic app that has a user provider with a signup() method:

doSignup() {
  // set         


        

Answer 1

I was using ngrx with Angular to store the token. I faced this error in my interceptor.ts.

The wrong code was this:

intercept(req: HttpRequest, next: HttpHandler): Observable> {

        this._store
            .pipe(
                select(fromSelectors.selectAuth),
            )
            .subscribe((state: fromReducers.AuthState) => {

                if (state.token != null) {
                    const clonedReq = req.clone({
                        headers: req.headers.set('Authorization', 'Bearer ' + state.token)
                    });
                    return next.handle(clonedReq);
                }
                else {
                    this.router.navigate(['login']);
                }
            });
    }

I fixed the code by returning the flow:

 intercept(req: HttpRequest, next: HttpHandler): Observable> {

        return this._store
            .pipe(
                select(fromSelectors.selectAuth),
                switchMap((state: fromReducers.AuthState) => {

                    if (state.token != null) {
                        const clonedReq = req.clone({
                            headers: req.headers.set('Authorization', 'Bearer ' + state.token)
                        });
                        return next.handle(clonedReq);
                    }
                    else {
                        this.router.navigate(['login']);
                        // return EMPTY stream
                        return of({}) as Observable>;
                    }
                })
            );

    }