Failed to load mods: Subsurface/data-final-fixes.lua:133: attempt to index field 'subsurface-hole' (a nil value)
stack traceback:
Subsurface/data-final-fixes.lua:133: in main chunk

Did this occur after updating or when you installed the mod for the first time?

I think after updating and starting a new game.
but, should not one always check for nil?

Do you have other mods installed? A mod seems to remove that entry
Can you send me your factorio-current.log and savegame?

this error is happening when I try and enable it in my current game. it will not load.

Do you still want the log? and how do you want it?

Yes, pls send it via cloud or something

Jumping onto this as I'm getting a similar error. I've got the current log pulled and a copy of the save. How do you want me to get you the google drive link to you? Error I'm getting is below. The mod is being added mid game but I have confirmed the error happens in a new sandbox save as well.
Error while running event Subsurface::on_built_entity (ID 6)
Subsurface/scripts/resources.lua:113: attempt to call field 'merge' (a nil value)
stack traceback:
Subsurface/scripts/resources.lua:113: in function 'copy_resource_data'
Subsurface/control.lua:210: in function 'get_subsurface'
Subsurface/control.lua:517: in function 'replace_surface_drill_dummy'
Subsurface/control.lua:572: in function <Subsurface/control.lua:560>

Alright, fixed this

Still have bug when loaded to existing
Error ModManager.cpp:1767: Failed to load mod "Subsurface": Subsurface/data-final-fixes.lua:133: attempt to index field 'subsurface-hole' (a nil value)
stack traceback:
Subsurface/data-final-fixes.lua:133: in main chunk

Does it occur without any other mods enabled?