For some reason when I reload a multiplayer save it errors and I cannot continue.

This is with Teams and Modmash Splinter Underground.
https://mods.factorio.com/mod/TeamCoop < this mod.

Error while running event modmashsplinterunderground::on_tick (ID 0)
...splinterunderground__/prototypes/scripts/underground.lua:741: attempt to index local 'p' (a nil value)
stack traceback:
...splinterunderground__/prototypes/scripts/underground.lua:741: in function 'local_check_teleport'
...splinterunderground__/prototypes/scripts/underground.lua:1529: in function <...splinterunderground__/prototypes/scripts/underground.lua:1526>

when i disable it, it just doesnt work together, but for some reason one of my saves (with all mods present) does work when i load it into multiplayer.
(Only difference is that the save is a bit older) but no mods were updated in the meantime so im confused.