send callback on http error

http-request-with-error.ts

public deleteItem(id: number, callback?: any): Observable<{}> {
    
    //some prepartion of the http request...

    return this.http.request(path, requestOptions)
            .map((response: Response) => {
               //some stuff...
            }).catch((error: any) => {
                error.callback=callback;
                return Observable.throw(error);
            });
}