Error "Die angeforderte Seite konnte nicht gefunden werden" in checkout/step5save

Error "Die angeforderte Seite konnte nicht gefunden werden" in checkout/step5save

After Update to PHP 8.0.24, Joomla 3.10.11 and JoomShopping 4.18.9 I get an error after confirming checkout step:

Unsupported operand types: int + string
/mnt/web002/b2/28/51289328/htdocs/allesapfel.de/components/com_jshopping/lib/tcpdf/tcpdf.php:1648

# Function Location
1 () JROOT/components/com_jshopping/lib/tcpdf/tcpdf.php:1648
2 TCPDF->Image() JROOT/components/com_jshopping/lib/generete_pdf_order.php:29
3 JorderPDF->addTitleHead() JROOT/components/com_jshopping/lib/generete_pdf_order.php:22
4 JorderPDF->addNewPage() JROOT/components/com_jshopping/lib/generete_pdf_order.php:73
5 generatePDF() JROOT/components/com_jshopping/tables/order.php:651
6 jshopOrder->generatePdf() JROOT/components/com_jshopping/models/ordermail.php:118
7 jshopOrderMail->send() JROOT/components/com_jshopping/models/checkout.php:32
8 jshopCheckout->sendOrderEmail() JROOT/components/com_jshopping/models/checkoutorder.php:39
9 jshopCheckoutOrder->orderDataSave() JROOT/components/com_jshopping/controllers/checkout.php:405
10 JshoppingControllerCheckout->step5save() JROOT/libraries/src/MVC/Controller/BaseController.php:702
11 Joomla\CMS\MVC\Controller\BaseController->execute() JROOT/components/com_jshopping/jshopping.php:25
12 require_once() JROOT/libraries/src/Component/ComponentHelper.php:402
13 Joomla\CMS\Component\ComponentHelper::executeComponent() JROOT/libraries/src/Component/ComponentHelper.php:377
14 Joomla\CMS\Component\ComponentHelper::renderComponent() JROOT/libraries/src/Application/SiteApplication.php:194
15 Joomla\CMS\Application\SiteApplication->dispatch() JROOT/libraries/src/Application/SiteApplication.php:233
16 Joomla\CMS\Application\SiteApplication->doExecute() JROOT/libraries/src/Application/CMSApplication.php:225
17 Joomla\CMS\Application\CMSApplication->execute() JROOT/index.php:49

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Aw: Error "Die angeforderte Seite konnte nicht gefunden werden" in checkout/step5save

seems to be PHP 8 problem. After restoring PHP 7 it works.

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Aw: Error "Die angeforderte Seite konnte nicht gefunden werden" in checkout/step5save

configuration / Shop info

PDF Config:
Set width / height (not empty)