Fatal exception when trying to save User model

When trying to save User model, I'm getting fatal exception.

Environment Phalcon: v3.2 UserPlugin: v3.0.x PHP: v7.2.x Server: Apache / PHP-FPM

Code triggering error:

      $user  = User::findFirst($this->auth->getUserId());
      $user->assign( [
          'first_name'  => $this->request->getPost('first_name'),
          'last_name' => $this->request->getPost('last_name'),
          'modified' => date('Y-m-d H:i:s')
        ] );
      $user->save();

This code snippet is responsible lib/Models/User/User.php:

    /**
     * Validations and business logic.
     */
    public function validation()
    {
        $this->validate(new Uniqueness(
            array(
                'field' => 'email',
                'message' => 'The email is already registered',
            )
        ));

        return true !== $this->validationHasFailed();
    }

Exception

( ! ) Deprecated: Function Phalcon\Mvc\Model\Validator::__construct() is deprecated in /var/www/project/vendor/crada/phalcon-user-plugin/lib/Models/User/User.php on line 871
Call Stack
#  Time  Memory  Function  Location
1  0.0000  403648  {main}( )  .../index.php:0
2  0.0008  434472  handle ( )  .../index.php:42
3  0.0011  457912  dispatch ( )  .../index.php:42
4  0.0014  464872  callActionMethod ( )  .../index.php:42
5  0.0014  465256  UserController->registerAction( )  .../index.php:42
6  0.0205  594832  save ( )  .../UserController.php:137
7  0.0206  595336  _preSave ( )  .../UserController.php:137
8  0.0208  598592  fireEventCancel ( )  .../UserController.php:137
9  0.0208  599024  Phalcon\UserPlugin\Models\User\User->validation( )  .../UserController.php:137

( ! ) Fatal error: Uncaught TypeError: Argument 1 passed to Phalcon\Mvc\Model::validate() must implement interface Phalcon\ValidationInterface, instance of Phalcon\Mvc\Model\Validator\Uniqueness given in /var/www/project/vendor/crada/phalcon-user-plugin/lib/Models/User/User.php on line 871
( ! ) TypeError: Argument 1 passed to Phalcon\Mvc\Model::validate() must implement interface Phalcon\ValidationInterface, instance of Phalcon\Mvc\Model\Validator\Uniqueness given in /var/www/project/vendor/crada/phalcon-user-plugin/lib/Models/User/User.php on line 871
Call Stack
#  Time  Memory  Function  Location
1  0.0000  403648  {main}( )  .../index.php:0
2  0.0008  434472  handle ( )  .../index.php:42
3  0.0011  457912  dispatch ( )  .../index.php:42
4  0.0014  464872  callActionMethod ( )  .../index.php:42
5  0.0014  465256  UserController->registerAction( )  .../index.php:42
6  0.0205  594832  save ( )  .../UserController.php:137
7  0.0206  595336  _preSave ( )  .../UserController.php:137
8  0.0208  598592  fireEventCancel ( )  .../UserController.php:137
9  0.0208  599024  Phalcon\UserPlugin\Models\User\User->validation( )  .../UserController.php:137

calinrada / PhalconUserPlugin

Fatal exception when trying to save User model #41