是一个验证登录的代码，验证代码为

<?php declare (strict_types = 1);  namespace appadmincontroller;  use thinkfacadeView; use thinkRequest; use appadminvalidateLogin as L; use thinkexceptionValidateException;  class Login{     //     public function index(Request $request){         if($request->isPost()){             $data = $request->post();             $remember = $data['remember'] ?? 0;             try{             $result = validate(L::class)->check($data);//halt($result);             }catch(ValidateException $e){                 halt($e);             }                      }         return View::fetch();     } } 

验证器的代码为:

<?php declare (strict_types = 1);  namespace appadminvalidate;  use thinkValidate;  class Login extends Validate {     /**      * 定义验证规则      * 格式：'字段名' =>  ['规则 1','规则 2'...]      *      * @var array      */     protected $rule = [         'username' => 'require|alphaNum|max:20',         'password' => 'require|alphaNum|length:6,16',     ];      /**      * 定义错误信息      * 格式：'字段名.规则名' =>  '错误信息'      *      * @var array      */     protected $message = [         'username.require' => '账号不能为空',         'password.require' => '密码不能为空',         'username.alphaNum' => '账号只能包含字母和数字',         'username.max' => '账号字符最大长度为 20',         'password.alphaNum' => '密码只能包含字母和数字',         'password.length' => '密码的长度为 6 ～ 16',     ]; }  

执行后报这个错误，请问是哪里出了问题？

#0 [0]Error in Validate.php line 1600 Call to a member function has() on null      * @param string $msg   错误信息      * @param mixed  $rule  验证规则数据      * @param string $title 字段描述名      * @return string|array      */     protected function parseErrorMsg(string $msg, $rule, string $title)     {         if (0 === strpos($msg, '{%')) {             $msg = $this->lang->get(substr($msg, 2, -1));         } elseif ($this->lang->has($msg)) {             $msg = $this->lang->get($msg);         }          if (is_array($msg)) {             return $this->errorMsgIsArray($msg, $rule, $title);         }          // rule 若是数组则转为字符串         if (is_array($rule)) {         ```