Discovered today on Vector 2022 master branch, there appears to be a blank space where the ToC would be on Vector 2022 special pages.
By checking out git commits in Vector one-by-one, a related change was introduced in on January 13, with [[https://gerrit.wikimedia.org/r/c/mediawiki/skins/Vector/+/879651 | Table of contents elements should not be rendered where none available ]] (which sounds like it should prevent this very problem).
Somehow this has only appeared recently and does not affect production. Potentially could be a core change that changes the value of the `data-toc` array from null to an empty array (guessing).
The following patch explicitly sets `null` on the ToC array and fixes this issue:
### Developer notes
The CSS issue is due to a missing class "vector-sidebar-container-no-toc", which is set when `data-toc` evaluates to false in mustache.