code: function onError (err) {
        if (!responded) {
          errState = true;
          responded = true;
          callback(err);
  
          //
          // Remove listeners to related events.
          //
          drone.removeListener('exit', onExit);
          drone.removeListener('message', onCarapacePort);
          clearTimeout(timeout);
        }
      }
docs: If the `forever.Monitor` instance emits an error then pass this error back up to the callback.  (remark) this may not work if haibu starts two apps at the same time