code: function _looksLikeAYHTTPError(err) {
    return err instanceof YHTTPError || (
       err.constructor &&
       err.constructor.name &&
       err.constructor.name.endsWith('Error') &&
      'string' === typeof err.code && _looksLikeAYHTTPErrorCode(err.code) &&
      'number' === typeof err.httpCode &&
      err.params && err.params instanceof Array
    );
  }
docs: In order to keep compatibility through major versions we have to make kind of an cross major version instanceof