Space missing between css selectors in Product Listing

-- HikaShop version -- : 4.1.0
-- Joomla version -- : 3.9.6
-- PHP version -- : 7.2.18
-- Error-message(debug-mod must be tuned on) -- : None

A minor issue but has caught me out a couple of times: To reproduce:

1. Add a new 'Product listing' menu item and in the 'Product options' tab select 'list' and add a UL class name.
   
   
2. Save and examine the code produced and you will notice that there is no space between the class selectors.