Mass action failure after Joomla update

-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.4
-- Error-message(debug-mod must be tuned on) -- : Notice: Undefined property: stdClass::$joomla_users in /home/underdev/public_html/hunterxci/administrator/components/com_hikashop/classes/massaction.php on line 363

Warning: Invalid argument supplied for foreach() in /home/underdev/public_html/hunterxci/administrator/components/com_hikashop/classes/massaction.php on line 363

Help!
I have a mass action setup to export a CSV file when an order is created. It was working fine in Joomla 3.3.6 but now after updating to 3.4 it does not create the CSV file and when I try and process the action in the backend I get:

Notice: Undefined property: stdClass::$joomla_users in /home/underdev/public_html/hunterxci/administrator/components/com_hikashop/classes/massaction.php on line 363

Warning: Invalid argument supplied for foreach() in /home/underdev/public_html/hunterxci/administrator/components/com_hikashop/classes/massaction.php on line 363

What is going wrong?

Hi,

It seems that there is an issue with the example data. Please check if you have orders assigned to the user with the address "john@hikashop.com". If it is, please delete these orders.

If you don't have that kind of orders, then the error can come from an entry error in the #__hikashop_user table, a user_cms_id is maybe not corresponding to any id in the table #__users.