headingmode parameter causes an error

[irish-brigid]

DynamicPageList3 version: 3.6.1
MediaWiki version: 1.43.0
PHP version: 8.2.12 (apache2handler)

List of steps to reproduce (step by step, including full links if applicable):

• Use either {{#dpl ... }} or <dpl>...</dpl> tags and specify categories
• Insert parameter ordermethod=[any two]
• Insert headingmode=[any]

What happens?:
[42d1224b86fcadb4edab8383] Caught exception of type TypeError

The random string of letters and numbers is different every time.

What should have happened instead?:
A page with something like this:
Category
Page 1
Page 2
Page 3

Browser information, screenshots and other applicable information:
Firefox 135.0