Hi I get this error when running two trains together.
it seems to happen when the train goes thru a corner.
the corner has got signals on it.

Error while running event ShuttleTrainRefresh::on_nth_tick(617)
LuaTrain API call when LuaTrain was invalid.
stack traceback:
[C]: in function 'index'
__ShuttleTrainRefresh/script/train.lua:263: in function 'untrackTrain'
ShuttleTrainRefresh/script/train.lua:174: in function <ShuttleTrainRefresh/script/train.lua:169>

Hey Dobbie, thanks for reporting, I will look into it asap.

Fixed in version 1.0.1, should be available within the next couple of minutes.