code: public function getFirstError($attribute = null)
      {
          if (!$this->errors) {
              return null;
          } elseif (is_null($attribute)) {
              $errors = $this->getErrors();
              reset($errors);
              $firstError = current($errors);
              $arrayKeys = array_keys($firstError);
              $error = $firstError[$arrayKeys[0]];
              return $error;
          }
  
          return parent::getFirstError($attribute);
      }
docs: Returns the first error in the model
  @author Olawale Lawal <wale@cottacush.com>
  @param string $attribute
  @return string