与HttpInterceptor observables发布混合承诺？

我正在使用HttpInterceptor重新发送带有令牌的请求，以防它们返回401.这之前我刚刚使用缓存令牌时运行良好 . 由于Firebase令牌似乎没有自动刷新（尽管使用forceRefresh），我现在正试图在拦截器类中实时获取新的令牌 . 问题是现在请求没有被重新发送 .

这是我的完整拦截器：

export class CustomHttpInterceptor implements HttpInterceptor {
    constructor(private injector: Injector) {
    }

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

        const formRequest = req.clone({ headers: req.headers.set('Content-Type', 'application/x-www-form-urlencoded') });

        return next.handle(formRequest).map((event: HttpEvent<any>) => {
            if (event instanceof HttpResponse) {
                console.log("GOT RESPONSE WITHOUT ERROR. JUST PASSING THROUGH.");
                return event;
            }
        }).catch(err => {
            console.log("==INTERCEPTOR== CATCH ERROR RESPONSE");
            if (err instanceof HttpErrorResponse) {
                console.log("==INTERCEPTOR== IS HTTP ERROR RESPONSE");
                if (err.status === 401) {
                    console.log("==INTERCEPTOR== IS 401");
                    let postParams = new HttpParams({ fromString: req.body });
                    if (postParams.has('t')) {
                        //401 while we already provided a token, so a real login is required
                        console.log("==INTERCEPTOR== PROVIDED TOKEN, STILL PROBLEM");
                        throw new Error("NOT_AUTH");
                    } else {
                        // most likely session expired, resend token
                        console.log("==INTERCEPTOR== REQUEST WAS WITHOUT TOKEN, RESEND WITH TOKEN");
                        // get AuthProvider here
                        const auth = this.injector.get(AuthProvider);
                        // token will come in a promise
                        return auth.getToken().then(idToken => {
                            console.log("GOT NEW TOKEN, resending request with token " + idToken);
                            //add token to post params
                            let newPostParams = postParams.append('t', idToken); ====> SUCCESFULLY GOT NEW TOKEN
                            //clone request and add new body
                            const changedReq = formRequest.clone({
                                method: 'POST',
                                body: newPostParams.toString()
                            });
                            return next.handle(changedReq);   ====> THIS IS NOT PERFORMED
                        },
                        error => {
                            throw(error);
                        });
                    }
                }
            } else {
                throw(err);
            }
        })
    }
}

如果没有此promise函数来获取新令牌，则使用最后一个“next.handle（changedReq）;”重新发送请求 . 我在这里找不到我做错的事 . 这是因为我将承诺与可观察者混合在一起吗？