https://paste.ee/p/gN2fE

Nullpointer on this line:
https://github.com/DimensionalDevelopment/DimDoors/blob/1.12-WIP/src/main/java/org/dimdev/dimdoors/shared/tools/SchematicConverter.java#L120
Caused by this method call returning null:
TileEntity.getKey(TileEntityHopper.class)

But only when Foamfix is installed.

Yeah, FoamFix replaces the TileEntityHopper with TileEntityFasterHopper. A workaround would be hardcoding the IDs.