How severely does this bug affect you? It’s annoying but I can work around it.
Well, I reckon this is the wrong behavour, and so calling it a bug.
The count node should go negative if decremented from 0.
If the above is argued against, then if I set the initial value to a high value then it should drop below that value on decrement.
While I try to spend some time debugging before uploading a bug report, the count node would have a pretty hard time if it had to count every time I posted something where I was wrong or posted a dumb question ;)