Updating AoP to the newest version causes this crash, because the newest version removed the smeltery once and for all, and you don't have a sanity check to catch this...

Failed to load mods: molten_plastic/prototypes/compat.lua:1348: attempt to index global 'molten_plastic' (a nil value)
stack traceback:
molten_plastic/prototypes/compat.lua:1348: in main chunk
[C]: in function 'require'
molten_plastic/data.lua:5: in main chunk

Hey there,

I've suspended the AoP compatibility patch, I'll remake it once the AoP rework is finished.

Thanks for the report!