Yii2 passing empty login?

Question

Yii

Hello! I did registration and authorization according to the lesson, but in the end for some reason the username does not pass to me

SiteController

public function actionSignup(){
 if (!Yii::$app->user->isGuest) {
 return $this->goHome();
 }
 $model = new SignupForm();
 if($model->load(\Yii::$app->request->post()) && $model->validate()){
 $user = new User();
 $user->username = $model->username;
 $user->password = \Yii::$app->security->generatePasswordHash($model->password);
 if($user->save()){
 return $this->goHome();
 }
 }

 return $this->render('signup', compact('model'));
}

dumped the username dump everything! and the error is (prnt.sc/u86hfb)

mistake

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '' for key 'username'
The SQL being executed was: INSERT INTO `user` (`id`) VALUES (DEFAULT)
Error Info: Array
(
    [0] => 23000
    [1] => 1062
    [2] => Duplicate entry '' for key 'username'
)
↵
Caused by: PDOException
SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '' for key 'username'