I come across a lot of edits where people trying to point out something to the OP. Sometimes it contains useful information that would benefit everyone reading it. Still it is invalid because it radically change the post / modify the code. Mostly they come from new users but what triggered me to start this is that I found similar edits coming from users with 1k+ rep.
This edit; the user modified the code and added this warning:
be careful, in case
anything + NULLwill generate
Add reject reason: Rejected because it is a comment. This will send the users a notification with a link to redirect them to the post with their edit/comment entered in the comments box to review and post it correctly.