Error on startup log listed as

96.269 Error ModManager.cpp:1767: Failed to load mod "rigor-module": rigor-module/data-final-fixes.lua:522: attempt to index field '?' (a nil value)
stack traceback:
rigor-module/data-final-fixes.lua:522: in main chunk
96.303 Loading mod core 0.0.0 (data.lua)
97.577 Checksum for core: 1551277403
97.666 Error ModManager.cpp:1767: Error in assignID: recipe-category with name 'recycling' does not exist.

Thanks for reporting! Can you provide your mod list when you hit this bug?

Edit: assuming it's the same here

Will be fixed with the next update.

Confirmed i can run v6.4