code: public function addPredefinedError($id, $message = '')
      {
          if (is_array($id)) {
              $this->errorList = array_diff_key($this->errorList, $id) + $id;
          } else {
              $this->errorList[$id] = $message;
          }
      }
docs: Adds a predefined error to the internal list
  
  @param int|array $id Must be numeric or associative array with numeric keys
  @param string    $message