拦截器问题-TypeError：您在期望流的位置提供了“未定义”。您可以提供一个Observable，Promise，Array或Iterable

Question

我正在尝试使用.netcore webapi和Angular 7进行登录。我认为在拦截器中存在问题，请帮我解决这个问题。

@Injectable()
export class AuthInterceptor implements HttpInterceptor{

    constructor(private router:Router) { }

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>>{
        if(localStorage.getItem('token')!=null){
            const cloendReq = req.clone({
                headers: req.headers.set('Authorization','Bearer ' +localStorage.getItem('token'))
            });
            return next.handle(cloendReq).pipe(
                tap(
                    succ =>{ },
                    err =>{
                        if(err.status = 401){
                        localStorage.removeItem('token');
                        this.router.navigateByUrl('/user/login');
                        }
                    }
                )
            )
        }
         else next.handle(req.clone());
    }
}

Here is the error

登录

onSubmit(form:NgForm){
this.service.login(form.value).subscribe(
  (res: any)=>{
    localStorage.setItem('token',res.token);
    this.router.navigateByUrl('/home');
  },
  err =>{
    if(err.status == 400)
      this.toster.error('Incorrect UserName or Password','Authantication Failed!')
    else
      console.error(err)
  }
);
}