Issue Description:

When loading the game with the given configuration for any said biome the game will crash with a ConcurrentModificationException. Details of this crash and the file causing it can be seen below under additional information.

The problem occurs when trying to parse or more accurately use the JSON provided for a generation feature and trips up for emeralds not accepting the enable flag as false for some obscure reason.

Steps to reproduce:

1. Use the given versions, and configuration files
2. Load the game
3. Expect crash during the pre Init/Init phase

Additional Information:

• fml-client-latest.log or fml-server-latest.log latest.log: https://pastebin.com/Hy90U69V
• Crash-Reports: https://pastebin.com/0thQRVGf
• Config (config/biomesoplenty/biomes/alps.json): https://pastebin.com/1XtKa6HG

Affected Version(s) (Exact numbers, do NOT use "latest"):

• Java: 1.8.0_25 (64-bit)
• Minecraft: 1.12.2
• Minecraft Forge: 14.23.0.2515
• Biomes O' Plenty: 7.0.1.2297

@GirafiStudios I had yes. @Adubbz Thank you for fixing this so quickly. Very much appreciated ❤️

Essentially what's happening is you're not allowing the enable flag to be what controls the features' enabled or disabled state. Which makes wanting to disable all features incredibly painstaking and far from user friendly. 😕

For example, to get alps to work, I had to set stone_formations all the gems and miners_delight to "amountPerChunk": 0. Which fine, Isn't too bad (I only had to spend an hour going through each feature to find out which of them it was causing that to happen on). However, then loading these new rules for all the other biomes still failed to work.

Have you removed everything else from alps.json, except the emeralds part?
Or are you just showing the part you changed?