php 8.1 preg_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated

[TwentyZeroTwo]

Encountered when editing a page at /wp-admin/post.php?post=2&action=edit

On line 6811 of wp-includes/post.php

 $ext     = preg_replace( '/^.+?\.([^.]+)$/', '$1', $file );

I found a lot of these tickets on trac, but couldnt find any for this specific instance.

[rajinsharwar]

Hi @TwentyZeroTwo, can you try to remove, and re-attach the any attachments in the post?

[TwentyZeroTwo]

I can indeed, but surely the underlying deprecation error should be corrected?