Hi. Thank you for continuing to work on this mod.
I was really waiting for SE 2.0 to be released, and for some reason I really wanted to launch a train from the subway into space using a space elevator.

When I was testing this, I launched the sandbox and found that in editor mode this mod causes an unavoidable error when I tried to open the train menu and enable remote viewing on the space elevator, also once for some reason it crashed when I put a cargo rocket silo.
At the same time, everything seems to be working well in normal mode.
That's all I found.

Well, also, if you demolish the tunnel while the train is passing through it, and then put the tunnel in the same place, the mod will also cause an unavoidable error, but I don't think it can be caused by accident)

Can you please post all the error messages?

Well, also, if you demolish the tunnel while the train is passing through it, and then put the tunnel in the same place, the mod will also cause an unavoidable error, but I don't think it can be caused by accident)

I could reproduce and fix this

With any of the above listed actions in the editor:
Error while running event Subsurface::on_player_controller_changed (ID 59)
＿＿Subsurface＿＿/control.lua:891: attempt to index local 'character' (a nil value) stack traceback:
＿＿Subsurface＿＿/control.lua:891: in function <＿＿Subsurface＿＿/control.lua:887>

Tunnel error:
Error while running event Subsurface:: on_built_entity (ID 6)
＿＿Subsurface＿＿/scripts/trains.lua:8: attempt to index local 'rail' (a nil value) stack traceback:
＿＿Subsurface＿_/scripts/trains.lua:8: in function 'subway_built'
＿＿Subsurface＿＿/control.lua:583: in function <＿＿Subsurface＿＿/control.lua:554>