Show modal dialog from HttpInterceptor

@Injectable()
export class MyInterceptor implements HttpInterceptor
{
    intercept(req : HttpRequest<any>, next : HttpHandler) : Observable<HttpEvent<any>>
    {
//show a modal dialog to hold the request until user respond/close the dialog
        if(ShowModalDialog())
        {
            return next.handle(req);
        }
        else
        {
//route to login
        }
    }
}

I have tried to show an angular material dialog, but it does not block the request and it continues executing next line.

I need to know how to show a modal dialog from interceptor when a request error response appears, show user some options and resume execution after dialog is closed.

Is it possible to stop/hold a request with such dialog?

You can do this with an angular material dialog:

@Injectable()
export class MyInterceptor implements HttpInterceptor {
  constructor(private dialog: MatDialog, private router: Router) {}
  
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    if(ShowModalDialog()) {
      return this.dialog.open(DialogModalComponent).afterClosed().pipe(
        concatMap(() => next.handle(req))
      );
    } else {
      return next.handle(req);
    }
  }
}