I just wasted a good hour on this, so I decided to post this here in case someone else is experiencing the same problem.
The cause of the issue is in \goodstore\templates\simple-shortcodes\page.php
if this function doesn't return an image url:
jaw_template_get_var('image_src');
then the actual HTML output will be:
<div class="row" style="background: url(' ');">
Because the URL is empty, this causes the page to reload in Firefox (haven't tested in other browsers). This was causing all sorts of issues when you try to add something to the cart - products were added twice because of the reload and in general the cart was not working properly.
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