Custom Forgot Password Laravel

selamat sore semuanya.

saya mau nanya nih gan. saya bikin autentikasi laravel kan ga pake auth (php artisan make:auth), jadi semua prosesnya itu bikin sendiri/custom. nah sekarang saya mau bikin forgot password, caranya gimana ya gan? saya bikin autentikasi pake sentinel. saya udah buat contoh proses forgot password dari internet, tapi muncul error.

 public function actforgot(Request $request){
        //return $request->email;
        //$user = user::whereEmail($request->email)->first();
        $user = user::where('email', $request->email)->get()->first();

        if($user->count() == 0){
            return back()->with('forgot', 'Reset code was sent to your email!');
        }

        $reminder = Reminder::exists($user) ?: Reminder::create($user);

        $this->sendEmail($user, $reminder->code);

        return back()->with('forgot', 'Reset code was sent to your email!');
    }

    private function sendEmail($user, $code){
        Mail::send('emails.forgot-password', ['user' => $user, 'code' => $code], function ($message) use ($user){
            $message->to($user->email);

            $message->subject("Hello $user->dealer_name, reset your password.");
        });
    }

terus muncul error kayak gini :

 Argument 1 passed to Cartalyst\Sentinel\Reminders\IlluminateReminderRepository::exists() must implement interface Cartalyst\Sentinel\Users\UserInterface, instance of App\User given, called in C:\newhppi\vendor\laravel\framework\src\Illuminate\Support\Facades\Facade.php on line 223

solusinya gimana ya gan? mohon bantuannya.