Custom dispatch type layout page

PHP 8.1, CS-Cart 4.20
I raised this issue with my theme provider, and they report the bug is in the default Responsive theme.
When I include a Meta description for a layout page with the dispatch type of Custom or Blog (example: Dispatch: Custom > products.on_sale {/index.php?dispatch=products.on_sale} or Custom > products.bestsellers or Custom > products.newest and Blog > page.view?page_type=B) I get the following notice written in the PHP error log for every page view. The log is really filling up with these notices - as much as 10MB per day.
(If I remove the Meta description the notice stops.)

PHP Deprecated

Message

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

Error at

app/lib/vendor/smarty/smarty/src/Extension/CallbackWrapper.php, line: 29

Backtrace

File: app/lib/vendor/smarty/smarty/src/Extension/CallbackWrapper.php
Line: 29
Function: {closure}
File: var/cache/templates/vivashop/ec4d468677398ee703a44ca7af238f389e93fd58_2.tygh_meta_description.override.tpl.php
Line: 42
Function: handle
File: app/lib/vendor/smarty/smarty/src/Template/GeneratedPhpFile.php
Line: 111
Function: content_69a9e71e615735_82757621
File: app/lib/vendor/smarty/smarty/src/Template/Compiled.php
Line: 110
Function: getRenderedTemplateCode
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 180
Function: render
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 655
Function: render
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 589
Function: _execute
File: app/Tygh/SmartyEngine/Core.php
Line: 85
Function: fetch
File: app/Tygh/SmartyEngine/Blocks/Hook.php
Line: 121
Function: fetch
File: var/cache/templates/vivashop/f55cfef08b63e900a7b0306ac84f4066e726285f_2.tygh_meta.tpl.php
Line: 163
Function: handle
File: app/lib/vendor/smarty/smarty/src/Template/GeneratedPhpFile.php
Line: 111
Function: content_69a9e71e5d7588_15147178
File: app/lib/vendor/smarty/smarty/src/Template/Compiled.php
Line: 110
Function: getRenderedTemplateCode
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 180
Function: render
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 287
Function: render
File: var/cache/templates/vivashop/29506607340f1acc447fda9b3e98c1615ec99151_2.tygh_index.tpl.php
Line: 120
Function: renderSubTemplate
File: app/lib/vendor/smarty/smarty/src/Template/GeneratedPhpFile.php
Line: 111
Function: content_69a9e71e566293_85274622
File: app/lib/vendor/smarty/smarty/src/Template/Compiled.php
Line: 110
Function: getRenderedTemplateCode
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 180
Function: render
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 655
Function: render
File: app/lib/vendor/smarty/smarty/src/Template.php
Line: 589
Function: _execute
File: app/Tygh/SmartyEngine/Core.php
Line: 85
Function: fetch
File: app/functions/fn.control.php
Line: 639
Function: fetch
File: index.php
Line: 19
Function: fn_dispatch