Laravel quotes Validator to report redirection error?

New LoginRequest

class LoginRequest extends Request
{
    public function authorize()
    {
        return false;
    }

    public function rules()
    {
        return [
            "username" => "required",
            "password" => "required",
            "captcha" => "required|captcha"
        ];
    }

    public function messages()
    {
        return [
            "username.required" => "!",
            "password.required" => "!",
            "captcha.required" => "!",
            "captcha.captcha" => "!"
        ];
    }
}

how to apply in LoginController controller?

class LoginController extends CommonController
{
    public function login(LoginRequest $request)
    {
        if ($request->isMethod("post")){
            $input = $request->all();
            $user = User::first();
            if ($user->username == $input["username"] && Crypt::decrypt($user->password) == $input["password"]){
                $request->session()->put("username", $input["username"]);
                return \redirect()->action("Admin\IndexController@index");
            }else{
//                $validator->errors()->add("errors", "!");
                return Redirect::back()->withErrors($validator);
            }
        }else{
            return view("Admin/login");
        }
    }
}

report a redirection error in this way

Mar.07,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3697b-4d6c4.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3697b-4d6c4.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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