[5.0] Deprecated: trim() ... when adding a tag in article

[waader]

Steps to reproduce the issue

• Joomla 5 nightly build (25.8.23)
• php 8.1.12
• MariaDB 10.4.27

I get this message in the error.log when I add a tag to an article:
PHP Deprecated: trim(): Passing null to parameter #1 ($string) of type string is deprecated in C:\xampp\htdocs\joomla5\components\com_tags\src\Controller\TagsController.php on line 39, referer: http://localhost/joomla5/administrator/index.php?option=com_content&view=article&layout=edit&id=12

Expected result

Actual result

System information (as much as possible)

Additional comments

[Hackwar]

Please test the fix for this in #41509. Since we have a PR, I'm closing this one.