[1.7.10]: MixinStructureGeneratorBaseMM (Mowzies mobs) doesn't work

[kotmatross28729]

Modpack

Custom

Help isloating the issue

• Did you tried to disabling some mixins in the mod config to see what mixin made the issue?
• Did you find what mixin made the issue?

Game log

https://mclo.gs/PwotTOn

crash report: https://mclo.gs/E1eV7ux

Description

For some reason, MixinStructureGeneratorBaseMM is not working properly and the game still crashes.
Although your Overwrite generateLayer looks like it should work, maybe there is some another thing that could be null? (It's unlikely to say this for sure, because in StructureGeneratorBase.java there are generally only 565 lines, and the report indicates line 742. which obviously doesn't exist. And the second line in the report - 380, contains only the use of the generateLayer method)