Magento Fix issue with Amasty Order Status extension

Hi,
I have Amasty Order Status extension and on some products it cause an error in checkout.
In the system.log the error is:

main.CRITICAL: TypeError: Amasty\OrderStatus\Model\AmOrderStatusRegistry::register(): Argument #1 ($status) must be of type string, null given, called in .../vendor/amasty/module-order-status/Plugin/Sales/Model/Order/RegisterOrderStatus.php on line 34 and defined in ..../vendor/amasty/module-order-status/Model/AmOrderStatusRegistry.php:52

RegisterOrderStatus.php on line 34:
$this->amOrderStatusRegister->register($result->getStatus());

AmOrderStatusRegistry.php on line 52:
public function register(string $status): void

I need some one to fix the issue.

ONLY FINAL BIDS!!!