Angular GlobalErrorHandler and HttpErrorResponse - Resolver throwing badly formatted HttpErrorResponse

Question

I've created global error handler in my Angular 6 application:

main error handler method:

handleError(error: Error | HttpErrorResponse) {
    const router = this.injector.get(Router);
    const notificationService = this.injector.get(NotificationsService);

    this._logger(error);

    if (!navigator.onLine) {
        notificationService.displayNotification('error', 'timespan', {heading: 'Internet connection lost!', body: ''});
    } else if (error instanceof HttpErrorResponse) {
        notificationService.displayNotification('error', 'click', this._httpErrorMessage(error));
    } else {
        // CLIENT error
        router.navigate(['/error-page']);
    }
}

Problem: Many of HTTP service calls are being performed in resolvers:

resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<ClientDetailsModel> {
if (route.params.cif) {
  const reqBody = new GetClientDetailsRequestModel({cif: route.params.cif, idWewPrac: this.userContext.getUserSKP()});
  return this.clientsService.getClientDetails(reqBody)
    .pipe(
        map((clientDetails: { customerDetails: ClientDetailsModel }) => {
            if (clientDetails.customerDetails) {
                return clientDetails.customerDetails;
            }
            return null;
        })
    );
}

If Http error occurs in such a call, error received by my global error handler is formed as HttpErrorResponse wrapped inside Error (message of Error is HttpErrorResponse):

Uncaught (in promise): HttpErrorResponse: {"headers":{"normalizedNames":{},"lazyUpdate":null},"status":400,"statusText":"OK","url":"https://...

If Http errors occurs outside of resolvers global error handler works perfectly fine.

To reach my goal (throwing HttpErrorResponse from resolver) I need to specify the way to handle error in error callback inside subscription, but I cannot do it because resolver is the one who manages subscription.

Is there a way to specify how resolver should handle errors?

I would like to avoid manual parsing of these wrapped errors.

Answer 1

I was searching for a solution, but could only create a work-a-round.

This will check for the HttpErrorResponse text and tries to parse the JSON which results into the real error object.

Not great at all, but better then nothing.

  handleError(error: any): void {
    console.error('Errorhandler catched error: ' + error.message, error);
    // We need to have this little hack in oder to access the real error object
    // The Angular resolver / promise wraps the error into the message, serialized as json.
    // So we extract this error again.
    // But first lets check if we actually dealing with an HttpErrorResponse ...
    if (error.message.search('HttpErrorResponse: ')) {
      // The error includes an HTTPErrorResponse, so we try to parse it's values ...
      const regex = new RegExp('^.*HttpErrorResponse:\\s(\\{.*\\})$');
      const matches = regex.exec(error.message);
      if (matches !== null) {
        // matches the regex, convert...
        const httpErrorResponse = JSON.parse(matches[1]); // This is now the real error object with all the fields
        this.handleHttpErrorResponse(httpErrorResponse);
      } else {
        // It contains HttpErrorResponse, but no JSON part...
        this.toastr.error('There was an unknown communication error',
          'Communication error',
          {timeOut: 10000});
      }
    } else {
      this.toastr.error('Unknown error occured',
        'Well that should not happen. Check the log for more information...',
        {timeOut: 10000});
    }
  }