Steps to reproduce the issue

Got to
/administrator/index.php?option=com_templates&view=styles
edit Beez3 index.php

Expected result

No PHP Warning: Trying to access array offset on value of type null
administrator\components\com_templates\views\template\tmpl\default_modal_resize_body.php on line 21
administrator\components\com_templates\views\template\tmpl\default_modal_resize_body.php on line 31

Actual result

PHP Warning

System information (as much as possible)

XAMPP
PHP 8.0
Joomla 3.9.24-rc

Additional comments