problem with saving products

-- HikaShop version -- : 3.4.0
-- Joomla version -- : 3.8.0

when i want to save product changes i receive " Call to undefined method hikashopProductClass::copy() in /home/SITENAME/public_html/administrator/components/com_hikashop/classes/product.php on line 1793"

Hello,

Can you please check the mentioned file ?
Because there is no mention of any "copy" function in our end.
So I got the impression that the file is not up to date in your side (you can check the header).

Regards,