Worldgen issue w/ Sponge 2990

[Excaliburning]

Hi ! It seems I recently crashed during worldgen using Sponge 1.12.2-2611-7.1.0-BETA-2990 (Forge 2611).

At the time, I was trying to generate a new world to test an issue noticed with Millénaire. When creating a past world w/ Millénaire I had no issue, it's unrelated. I also created a world without Millénaire but with Streams and had no issue (we've been playing in this world for two weeks by now).

Only when I tried to create a new world again, I got a crash during worldgen, as seen in the reports below.

The content displayed by the console : https://gist.github.com/Excaliburning/8d65531146f551a528bf62f37049b5b3

Crash report/log generated : https://gist.github.com/Excaliburning/784132c95cc8c02ccaf368fc24618c09

I also enabled chunk loading off-thread in Forge settings before that worldgen, could it be related to that ? I don't quite expect it but... better said than obfuscated. Thanks for your time and dedication !