Hi,
I don't think the problem is linked to HikaShop. You should normally have the same error if you edit a Joomla article.
In the Joomla plugins manager, edit the plugin called "FileSystem - Local", and check its settings. Make sure that the listed folders the actually exist (you can check via FTP or the cpanel file manager provided by your hosting). Normally, the "images" folder under the root folder of your website should be listed there. That's the folder usually used by Joomla to store the images and other media files.
Note that removing an entry for a folder in this plugin does not delete the folder or its content.
Regardless of whether or not you have changed anything, save its settings once. Then try again to access a product and you hopefully won't get the error anymore.