after upgrading to Joomla 4 and PHP 8.0 I have an issue with purity III and category lists on our municipal website. When clicking on a menu item that contains a category list I get the error message " 0 Attempt to modify property "params" on null" and the category list is not displayed.
I switched the PHP version back to 7.4 for now, turned on debugging and error messaging in the Joomla Backend and now the category lists show up again but all articles have an "expired label" behind them. Plus, I get the following errors and warnings:
**Warning: Creating default object from empty value in /homepages/8/d265690491/htdocs/vierinst/templates/purity_iii/html/com_content/category/default_articles.php on line 15
Warning: Use of undefined constant DS - assumed 'DS' (this will throw an Error in a future version of PHP) in /homepages/8/d265690491/htdocs/vierinst/templates/purity_iii/html/com_content/category/default_articles.php on line 36**
You can reproduce the above when clicking on one of the menu items containing category lists, for example: Top Menu Verwaltung: Menu item Amtsblätter, or Top Menu Neuching: Menu item Übernachtungen.
The site is a test domain, I am leaving the debugging on so you get the warning right there. The problem seems to be right there in line 15 and 36 of purity_iii/html/com_content/category/default_articles.php but I don't know what to do with that information. I urgently need to upgrade to PHP 8.0 and the problem seems to be directly connected to purity iii and PHP 8.0. Thank you for your help.