code: function checkLegacyResponse(responseObj) {
    // Handle the legacy Selenium error response format.
    if (responseObj
        && typeof responseObj === 'object'
        && typeof responseObj['status'] === 'number'
        && responseObj['status'] !== 0) {
      let status = responseObj['status'];
      let ctor = LEGACY_ERROR_CODE_TO_TYPE.get(status) || WebDriverError;
  
      let value = responseObj['value'];
  
      if (!value || typeof value !== 'object') {
        throw new ctor(value + '');
      } else {
        let message = value['message'] + '';
        if (ctor !== UnexpectedAlertOpenError) {
          throw new ctor(message);
        }
  
        let text = '';
        if (value['alert'] && typeof value['alert']['text'] === 'string') {
          text = value['alert']['text'];
        }
        throw new UnexpectedAlertOpenError(message, text);
      }
    }
    return responseObj;
  }
docs: Checks a legacy response from the Selenium 2.0 wire protocol for an error.
  @param {*} responseObj the response object to check.
  @return {*} responseObj the original response if it does not define an error.
  @throws {WebDriverError} if the response object defines an error.