Edit forum post error if parent is deleted

If you have:
1. a forum post and then
2. add a child post to it then
3. add a grandchild post to the child post
4. add a great-grandchild post to the grandchild post
5. delete child post

You now can't edit the grandchild post even though it has an edit button because it's 'parent' is deleted.

The file interaction/forum/editpost.php is the page that throws up the error:

   Not found
   The page you are looking for could not be found.

   Could not find post with id 2

You can however edit the great-grandchild post as it has a viable 'parent'.

Either you should be able to edit the child of a deleted parent - or you shouldn't be given an edit button if you can't.

My 2 cents believes you should be able to edit an orphan child as not having a parent is irrelevant to the text of the post that the child displays.