My problem is not so much unless as the problem it tries to fix - namely making doing something when a condition is false readable and clear. It does that, to an extent. But in 90% of the cases the code is for handling an error.
Marking cut and paste code as such is a great idea. The code needs some documentation anyway. It's all uncommented.update: fixed typo
Light a man a fire, he's warm for a day. Catch a man on fire, and he's warm for the rest of his life. - Terry Pratchet