Neu JTL 5.6.1 Settings page not saving

[payfro]

Hello,

We found a critical bug on JTL 5.6.1.

Behavior: Plugin Settings not showing on the settings page even though they are in the database.

Running a diff on GenericModelController.php will show the changes

diff shop-v5-6-1/includes/src/Router/Controller/Backend/GenericModelController.php shop-v5-5-0/includes/src/Router/Controller/Backend/GenericModelController.php

123c123
< if ($this->item !== null && $this->updateFromPost($this->item, Text::filterXSS($_POST)) === true) {
---
> if ($this->updateFromPost($this->item, Text::filterXSS($_POST)) === true) {

The condition `$this->item !== null && ` breaks the settings page.