Error message reads:

Failed to load mods: deadlock-beltboxes-loaders/prototypes/create_stack.lua:19: attempt to index field '?' (a nil value)
stack traceback:
deadlock-beltboxes-loaders/prototypes/create_stack.lua:19: in function 'get_group'
deadlock-beltboxes-loaders/prototypes/create_stack.lua:79: in function 'create_stacked_item'
deadlock-beltboxes-loaders/prototypes/public.lua:194: in function 'add_stack'
bzzirconium/zirconium-recipe-final-stacking.lua:7: in main chunk
[C]: in function 'require'
bzzirconium/data-final-fixes.lua:1: in main chunk
Mods to be disabled:
bzzirconium

P.S. Just so you know this is roughly the same message that is given with Lead and titanium (currently, I'm going through the process of trying to load all the mods and reporting what errors I get).