some fix

kernel/modules/user/service/UserService.php

@@ -3,6 +3,7 @@
 namespace kernel\modules\user\service;
 
 use kernel\FormModel;
+use kernel\helpers\Debug;
 use kernel\modules\user\models\User;
 
 class UserService
@@ -25,7 +26,9 @@ class UserService
     {
         $user->username = $form_model->getItem('username');
         $user->email = $form_model->getItem('email');
-        $user->password_hash = password_hash($form_model->getItem('password'), PASSWORD_DEFAULT);
+        if ($form_model->getItem('password')) {
+            $user->password_hash = password_hash($form_model->getItem('password'), PASSWORD_DEFAULT);
+        }
         if ($user->save()){
             return $user;
         }