Describe the bug
Setting a music area using a Recurrent Complex command block sometimes crashes the game.

Where playing in SinglePlayer or Multiplayer?
-SinglePlayer

To Reproduce
Steps to reproduce the behavior:

1. Create a world
2. Create a Recurrent complex structure with multiple script blocks with the command /area {AREA NAME} ~3 ~ ~3 ~-3 ~6 ~-3 false false
3. When generating the structure, theres about a ~30% chance of the game crashing

Expected behavior
The game should run the commands and create the area without crashing

Mods used or modpack (please complete the following information):

• Mods
  ambience music mod
  recurrent complex

• some more, but tested with just reccomplex ambience and the same bug happens.
  **Mod Version used:
  -1.12.2 1.7.6

**Please send the followings files to help track the issue:

ambience.txt

(Latest.log is too large to upload)

crash-2020-11-24_15.04.32-client.txt

Additional context
I am currently trying to put together a recurrent complex maze that generates with script blocks that set the area inside the maze to play a different soundtrack, but when generating the maze it crashes the game sometimes. Idk if this is to do with RC running multiple /area commands at the same time, or if its a conflict between your mod and RC.

by the error log appears that there is a concurrent modification exception, this happens because the two mods are trying to make changes to the world file at the same time, so it won't work with RC