I narrowed the crash down to an incompatibility with Lambent Nil. https://mods.factorio.com/mod/lambent-nil Trying to load the two mods together causes this error on startup.

3.419 Error ModManager.cpp:1623: Failed to load mod "GCKI": GCKI/libs/recipe-functions.lua:1111: attempt to compare number with string
stack traceback:
GCKI/libs/recipe-functions.lua:1111: in function 'get_difficulty_recipe_results'
GCKI/libs/recipe-functions.lua:1211: in function 'get_recipe_results'
GCKI/prototypes/3-add-circuits-to-vehicle-recipes.lua:149: in main chunk
[C]: in function 'require'
GCKI/data-final-fixes.lua:18: in main chunk

Hi, thanks for the report! However, while it is GCKI that is crashing, the reason for the crash is a mistake in the way Lambent Nil is defining the amount of a fluid recipe result . Actually, there are several instances of the same error.

I've filed a bug against Lambent Nil. If you don't want to wait untio that mod is updated, you can fix it yourself: Unpack the mod, open data/recipe.lua, and remove the quotes around the numbers given for amount in lines 153, 188, 225, 368, and 391.

Thanks for looking into it. I never thought Factorio would ignore an error in a mod when it is by itself but throw an error when combined with another mod. You even posted a fix and told the author of a mod that isn't yours. I am impressed.