It crashes once the cutscene is complete saying:
modmashsplinterunderground::on_cutscene_cancelled (ID 166)
...splinterunderground__/prototypes/scripts/underground.lua:446: bad argument #2 of 2 to 'random' (interval is empty)
stack traceback:
[C]: in function 'random'
...splinterunderground__/prototypes/scripts/underground.lua:446: in function 'generate_surface_area'
...splinterunderground__/prototypes/scripts/underground.lua:590: in function 'local_check_surface'
...splinterunderground__/prototypes/scripts/underground.lua:631: in function 'local_on_player_spawned'
...splinterunderground__/prototypes/scripts/underground.lua:636: in function <...splinterunderground__/prototypes/scripts/underground.lua:634>
stack traceback:
[C]: in function 'exit_cutscene'
...ata/Roaming/Factorio/temp/currently-playing/freeplay.lua:100: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

Can't quite see how this happens unless something else if messing up all resources, I will put something in to ensure the value calling the issue is at least one.