[Fixed] A bug where items 'Next page' and 'Previous page' can be overriden by 'Filler' items. [Fixed] A bug where 'Next page' and 'Previous page' were not displayed in the shop GUI. [Fixed] A bug where items in the shop editor on all pages except first, were a bit buggy and not able to edit them. [Fixed] A bug where item 'Next page' was displayed in the shop editor even if this page does not exist so causing console errors.