PHP Deprecated

trim(): Passing null to parameter #1 ($string) of type string is deprecated

app/addons/ab__multiple_cat_descriptions/controllers/frontend/categories.post.php, line: 31

File:	app/addons/ab__multiple_cat_descriptions/controllers/frontend/categories.post.php
Line:	31
Function:	{closure}
File:	app/functions/fn.control.php
Line:	728
Function:	include
File:	app/functions/fn.control.php
Line:	459
Function:	fn_run_controller
File:	index.php
Line:	19
Function:	fn_dispatch