"Warning: count(): Parameter must be an array or an object that implements Countable"

[sailorptah]

I've started getting this error at the top of my wiki's articles:

Warning: count(): Parameter must be an array or an object that implements Countable in /home/erinptah/public_html/leifandthorn/wiki/lib/plugins/metaheaders/action.php on line 62

Doesn't even have a CSS class that I could use to hide it from general view. The only way to get rid of it is disabling Metaheaders.

The wiki is here:
https://leifandthorn.com/wiki/doku.php?id=start

Also -- when the error message is there, a bunch of meta and link properties get moved to appear underneath it, i.e. inside the BODY tag. If I disable Metaheaders, or if you look at a non-article page like Recent Updates or Sitemap, they're back in HEAD where they belong.