May be more user-friendly than crashing the game.

The main reason I set it to throw an exception is anyone with 256 odd biomes must know how to alter the IDs. This way lets them know there world will have half/none of the oil biomes.

Their choice which biome to disable, the alternative is to get complaints about the lack of oil in certain mod packs or the like.

A GUI warning would be more user-friendly but another method would still be needed for servers.

Yup. I'm thinking, a log is enough. The biome is not absolutely required to enjoy BC experience anyway.

There has been no complains and no reports on that one. I'm assuming we're fine now, closing.