code: function handleError(body, response, callback) {
      var error;
      if (!body) {
          response.pipe(concat(function (body) {
              body = parseJSONBody(body);
              error = body.message || statusText(response.statusCode);
              callback(new Error(error), body, response);
          }));
      } else {
          error = body.message || statusText(response.statusCode);
          callback(new Error(error), body, response);
      }
  }
docs: Create an error object from the response and call the callback function
  @param   {Object}   body     The parsed response body (or null if not yet parsed)
  @param   {Response} response The HTTP response object
  @param   {Function} callback Function to call with the resulting error object
  @returns {void}