URL: canadaflagshop.com/shop
Zencart 1.5.8a
PHP 8.1.27
MySql 5.7
Host: Siteground
Plugins used - authorize.net AIM

Recently upgraded from 1.5.7d to 1.5.8a and I'm getting the following php warning in my logs folder each time a transaction is processed. The number of undefined array keys seems to correspond with the number of products on the related order. My includes/classes/ajax/zcAjaxPayment.php file is the original file with no modifications. Can anyone help?

Log info:
[17-Jan-2024 02:42:51 UTC] Request URI: /store/ajax.php?act=ajaxPayment&method=prepareConfirmation, IP address: xx.xx.xx.xx, Language id 1
#0 /home/customer/www/xxxxxx.com/public_html/store/includes/templates/responsive_classic/templates/tpl_ajax_checkout_confirmation_default.php(126): zen_debug_error_handler()
#1 /home/customer/www/xxxxxx.com/public_html/store/includes/classes/ajax/zcAjaxPayment.php(191): require_once('/home/customer/...')
#2 /home/customer/www/xxxxxx.com/public_html/store/ajax.php(85): zcAjaxPayment->prepareConfirmation()
--> PHP Warning: Undefined array key 0 in /home/customer/www/xxxxxx.com/public_html/store/includes/templates/responsive_classic/templates/tpl_ajax_checkout_confirmation_default.php on line 126.

[17-Jan-2024 02:42:51 UTC] Request URI: /store/ajax.php?act=ajaxPayment&method=prepareConfirmation, IP address: xx.xx.xx.xx, Language id 1
#0 /home/customer/www/xxxxxx.com/public_html/store/includes/templates/responsive_classic/templates/tpl_ajax_checkout_confirmation_default.php(126): zen_debug_error_handler()
#1 /home/customer/www/xxxxxx.com/public_html/store/includes/classes/ajax/zcAjaxPayment.php(191): require_once('/home/customer/...')
#2 /home/customer/www/xxxxxx.com/public_html/store/ajax.php(85): zcAjaxPayment->prepareConfirmation()
--> PHP Warning: Undefined array key 1 in /home/customer/www/xxxxxx.com/public_html/store/includes/templates/responsive_classic/templates/tpl_ajax_checkout_confirmation_default.php on line 126.


[17-Jan-2024 02:42:51 UTC] PHP Notice: ob_flush(): Failed to flush buffer. No buffer to flush in /home/customer/www/xxxxxx.com/public_html/store/includes/classes/ajax/zcAjaxPayment.php on line 193