What's the observable equivalent to `Promise.reject`

private handleError(error: any) {
    return Observable.throw('Some error information');
}

See also How to catch exception correctly from http.request()?

With RxJS 6 Observable.throw() has changed to throwError()

Observable.throw(new Error());

// becomes

throwError(new Error());

Source: RxJS v5.x to v6 Update Guide - Depracations