ePay payment plugin - callback fails with error 500

-- HikaShop version -- : 4.6.1
-- Joomla version -- : 4.1.4
-- PHP version -- : 8.0

Hi

I've bought your ePay payment plugin to use with recurring subscriptions. I've setup a test account at ePay/Bambora and added my server IP + domain in their control panel. My problem is, that the callback is not received by Hikashop. In my server log, I see that the callback results in a server error with code 500.

54.154.212.155 - - [28/Jul/2022:15:21:21 +0200] "GET /index.php?option=com_hikashop&ctrl=checkout&task=notify&notif_payment=bambora&tmpl=component&lang=da&Itemid=123&txnid=332727729&orderid=3&amount=100000&currency=208&date=20220728&time=1320&txnfee=0&subscriptionid=16610366&paymenttype=1&cardno=444444XXXXXX4000&hash=b0b70d9ae4d95bc24e25ecb2ae159077 HTTP/1.1" 500 6715 "-" "-"

54.77.224.116 - - [28/Jul/2022:16:09:24 +0200] "GET /index.php?option=com_hikashop&ctrl=checkout&task=notify&notif_payment=bambora&tmpl=component&lang=da&Itemid=123&txnid=332738932&orderid=8&amount=10000&currency=208&date=20220728&time=1609&txnfee=0&paymenttype=1&cardno=444444XXXXXX4000&hash=ad301cd67559cbb610f9d5ded85af1a9 HTTP/1.1" 500 2030 "-" "-"

From ePay callback response I see this error message: Attempt to assign property "txn_id" on null
Edit: Activated debug in Joomla and the stack trace points to JROOT/plugins/hikashoppayment/bambora/bambora.php:319

From the payment log:
Bambora transaction id: 332738250
07.28.22 14:01:54

Array
(
[option] => com_hikashop
[ctrl] => checkout
[task] => notify
[notif_payment] => bambora
[tmpl] => component
[lang] => da
[Itemid] => 123
[txnid] => 332738250
[orderid] => 6
[amount] => 100000
[currency] => 208
[date] => 20220728
[time] => 1559
[txnfee] => 0
[subscriptionid] => 16610868
[paymenttype] => 1
[cardno] => 444444XXXXXX4000
[hash] => 4a8ac4d3e8725d814e32de6d9341f667
)

EDIT again: on line 279 I changed $order_payment_params = null; to $order_payment_params = new stdClass();
Seems to have fixed the issue with the callback.

Another thing - there is an untranslated language constant "HANDLE_NO_RECURRING" - not sure what that setting is for?

Hello,

Thanks for your returns and your solution, on our side we will investigate more around this issue.
Can you confirm that the issue is completely solved ?

We will correct the small translation oversight in the language file for our future releases thanks to your feedback now!
Thanks again !

Regards