I had anormal start to the game but after the first warp I kept getting the same error message

Error while running event levelup::on_nth_tick(6)
levelup/control.lua:18: attempt to index field '?' (a nil value)
stack traceback:
levelup/control.lua:18: in function 'refresh_chunks'
levelup/control.lua:49: in function 'get_buildings'
levelup/control.lua:75: in function <levelup/control.lua:73>

Dunno if that is anything you can fix with it, but if you can many thanks!

unfortunately, it's something on the level up mod side.
It looks like it uses surfaces index (instead of looping over surfaces themselves) but not expecting non contiguous indexes (as surfaces in dimension warp are created/deleted as we warp), resulting in checking non existing surfaces.