Undefined index: customized_product_quantity

[Quant]

We have two ajax functions (ajaxProcessAddProductOnOrder, ajaxProcessEditProductOnOrder) to edit and add goods from BO that use the ./orders/_product_line.tpl template but do not define $product['customized_product_quantity'].
Accordingly, we have such a message in the error log:

2020/01/28 13:29:47 [error] 675#675: *124 FastCGI sent in stderr: "PHP message: PHP Notice:  Undefined index: customized_product_quantity in /home/vagrant/public_html/cache/smarty/compile/7c/80/09/7c80093774885aab8180ca74c940683e358afd6d_0.file._product_line.tpl.php on line 133PHP message: PHP Notice:  Undefined index: customized_product_quantity in /home/vagrant/public_html/cache/smarty/compile/7c/80/09/7c80093774885aab8180ca74c940683e358afd6d_0.file._product_line.tpl.php on line 133"