I have a clean install of Joomla 4.0.6 along with T4 Framework Latest Build. PHP 8.0.15. I was configuring t4_bs5_blank - Default template and after a while (about 2 hours exploring the template) the template style page in the backend broke with the following error "0 array_merge(): Argument #1 must be of type array, null given"
I'm not sure what has happened as I was just saving the template styles when the error happened. The only way I can now get back into the template styles is to change the PHP to 7.4.27