It just occurred to me that I'm very stupid, and 5 is 6 bigger than -1. So the bug was just that I was allowed to wager 3 coins, not the exploding. It was a very poor decision on my part to wager those 3 coins to see what would happen, haha. I did get the left side down to only 2 coins in an earlier game, and that time it didn't let me wager 3 coins, so it's possible it's just one side that isn't making that check. It's probably not an easy game condition to test, given the randomness of the game!