Failed to load mods: deadlock-beltboxes-loaders/prototypes/create_stack.lua:124: attempt to index field '?' (a nil value)
stack traceback:
deadlock-beltboxes-loaders/prototypes/create_stack.lua:124: in function 'create_stacking_recipes'
deadlock-beltboxes-loaders/prototypes/public.lua:195: in function 'add_stack'
...ger-ores/vanilla/compatibility/deadlock/data-updates.lua:15: in main chunk
[C]: in function 'require'
redmew-data/danger-ores/vanilla/data-updates.lua:8: in main chunk
[C]: in function 'require'
redmew-data/data-updates.lua:10: in main chunk

Hi I'm getting the above crash message when trying to load the mod in a save file.

Also when I load the mod on it's own in a new map the stacker boxes are not accepting any items.

I believe RedRafe has kindly suggested a potential fix on your github page:
https://github.com/shanemadden/factorio-deadlock-beltboxes-loaders/issues/39