protected function performLogin($user, $rememberMe = true)
    {
        // log user in
        $loginDuration = $rememberMe ? $this->module->loginDuration : 0;
        Yii::$app->user->login($user, $loginDuration);

        // check for a valid returnUrl (to prevent a weird login bug)
        //   https://github.com/amnah/yii2-user/issues/115
        $loginRedirect = $this->module->loginRedirect;
        $returnUrl = Yii::$app->user->getReturnUrl($loginRedirect);
        if (strpos($returnUrl, "user/login") !== false || strpos($returnUrl, "user/logout") !== false) {
            $returnUrl = null;
        }

        return $returnUrl;
    }