code: protected function formatEnumRule($rule)
      {
          if (!isset($rule['range'])) {
              throw new InternalServerError(
                  T("miss {name}'s enum range", ['name' => $rule['name']]));
          }
  
          if (empty($rule['range']) || !is_array($rule['range'])) {
              throw new InternalServerError(
                  T("{name}'s enum range can not be empty", ['name' => $rule['name']]));
          }
      }
docs: 检测枚举规则的合法性
  
  @param array $rule ['name' => '', 'type' => 'enum', 'default' => '', 'range' => []]
  @throws InternalServerError