[Admin]

This is not a "lousy design", since your hacking caused this error. Blaming this on Jelsoft is the last thing you can do about it.

The program expects the thread to be populated with posts, like all threads are (when you first create a thread, you will see in newthread.php that a post is created as well). When you have a post-less thread vBulletin can't get the postid of the first post, which causes that error.

And I also don't understand how 'open' is a "lousy variable name", the name suggests this field means "Is this thread open for new posts?", where 1 means "Yes, it is open" while 0 means "No, it is closed". I think it's a perfect name, don't you?