"Render %s callbacks must be methods of a class that implements" message wasn't updated for attribute

Tart0 → made their first commit to this issue’s fork.

Sorry to reviewers for the mess, got some trouble with PHPStan ^^'

Tart0 → changed the visibility of the branch 3436803-render-s-callbacks to hidden.

Tart0 → changed the visibility of the branch 3436803-render-s-callbacks to active.

The MR is making far too many changes -- it seems to be updating all the callbacks to use the attribute. Which is a good change, and there may be an other issue where you should contribute those changes so they're not wasted.

But this issue is about changing just one message string.