The game will crash if I try to set the cost to 214,748,365 (1/10th of max int, rounded), so I assume it is because it can't handle the overflow from trying to multiply it by 10 and store it as max energy storage.

Swap the data type/s so that it won't crash for the players like me who are trying to set astronomical numbers as cost.

Unfortunately, the Forge energy system seems to require integers. I'll lower the maximum to prevent those crashes, though. Sorry!