Hi! I just updated to 0.5.0 and got this crash:

1.611 Error ModManager.cpp:1469: Failed to load mod "math7UTBCostIncrease": __math7UTBCostIncrease__/data-final-fixes.lua:1: __math7UTBCostIncrease__/prototypes/recipe-final-fixes.lua:146: attempt to call method 'add_ingredient' (a nil value)
stack traceback:
__math7UTBCostIncrease__/prototypes/recipe-final-fixes.lua:146: in main chunk
[C]: in function 'require'
__math7UTBCostIncrease__/data-final-fixes.lua:1: in main chunk
stack traceback:
[C]: in function 'require'
__math7UTBCostIncrease__/data-final-fixes.lua:1: in main chunk
1.612 Loading mod core 0.0.0 (data.lua)
1.695 Checksum for core: 794957236
1.757 Error ModManager.cpp:1469: Error in assignID, recipe-category with name 'crafting' does not exist.

This also happened when no other mod (except your library mod) active. It would be nice if you could fix this. :-)

Seems like I didn't test enough... Fixed now (0.5.1). Additional testing also found a bug in the library which caused some belt recipes to be changed (while they shouldn't, of course), which is fixed with the new version of the library.

Thanks for reporting!