Hi,
The problem does not came from HikaShop.
HikaShop is called before the system plugin of jat3 which want to do something "irregular" by defining itself the joomla object JViewLegacy.
Because HikaShop uses JViewLegacy and call joomla thanks to a "jimport" in order to have the object JViewLegacy defined, the system plugin of jat3 crashes.
They should add some security to abort this crash and you should set a higher priority to their plugins so it could be instantiate before the HikaShop call.
If you really want to remove the "jimport", you can edit the HikaShop "helper.php" file and remove the two "jimport" at the beginning of the file.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.