cycle js HTTP wrapper, error handling

wrapHTTP.js

// Jan van Brügge @jvanbruegge
function wrapHTTP(http$) {
    return http$
        .map(res => res.replaceError(err => ({ type: 'left', value: err } as Either<Response, HTTPError>)))
        .flatten()
        .map(res => res.type === undefined ? { type: 'right', value: res } : res );
}

// mz3 @mz3
function wrapHTTP_Alt(http$) {

  const response$ = http$
    .map(res => res.replaceError(err => xs.of({err})))
    .flatten()
    .map(res => res.hasOwnProperty('err') ? res : {res});

  const success$ = response$.filter(obj => obj.hasOwnProperty('res')).map(obj => obj.res);
  const error$ = response$.filter(obj => obj.hasOwnProperty('err')).map(obj => obj.err);

  return {
    success$,
    error$
  };

};