Failed to load mods: ProductivityResearchForEveryone/functions.lua:56: attempt to index field '?' (a nil value)
stack traceback:
ProductivityResearchForEveryone/functions.lua:56: in function 'buildPrerequisitesWithoutTriggers'
ProductivityResearchForEveryone/data-final-fixes.lua:9: in main chunk

Does not crash for me on 2.0.21 with just Space Age and this mod active; same without Space Age. Can you share your modlist?

After updating 8 of my mods (including the update for this mod), it also no longer crashes, interesting! :D

Actually managed to reproduce it, the error happens if some other mod defines a technology prerequisite that does not exist (the game would just not load anyway in this case). Will be fixed in 1.0.4.

Awesome to hear that you found something, love skilled people doing skilled stuff, thank you!