http retryWhen that throws last error when retries are exhausted

retryWhenThrowsLastError.js

let retries = 0;
this.http
    .get(this.url)
    .retryWhen(error => {
               return error
                  .flatMap((error: any) => {
                     retries++;
                     if (retries <= 5 && error.status  === 503) {
                       return Observable.of(error.status).delay(1000)
                     }
                     return Observable.throw(error);
                  })
               });