Confirmed: Tutorial: How to crush client in 5 seconds


It's very important to fix this kind of bug, even though it's an edge case a typical user will never run into.
The reason is sometimes these bugs provide gateways for hacks and exploits. For example, if they also haven't coded carefully in other places, spending negative amounts of diamonds could result in the user having their diamond total *increased*, by millions, for free. With that consideration, I hope everyone can see how idiotic the 'what's the big deal' responses above actually are.