Fixed multiple bugs

【Contents of the fix】
■Fixed an error that occurred when using the page builder “Tab”.
■Fixed a bug that thumbnails are not displayed in the link to the next/previous article when there is an article with no eye catch.

The following are the files that have been fixed in this update.
【Fixed files】
functions/next_prev.php
pagebuilder/modules/tab.php
style.css

For more information, please visit the MAG(tcd036) download site for purchasers.