Error on adding products on the backend order

-- HikaShop version -- : 3.4.0
-- Joomla version -- : 3.8.6
-- PHP version -- : 7

Hi Hikashop team,

When we add a product on a back-end order we get this error:

Warning: reset() expects parameter 1 to be array, null given in ...../administrator/components/com_hikashop/views/order/tmpl/edit_products.php on line 41

Notice: Trying to get property of non-object in ....../administrator/components/com_hikashop/views/order/tmpl/edit_products.php on line 41

How can we fix this error?

thanks in advance.

Kind regards,
Lumiga