This doesn't seem to be game-breaking or really harm anything as far as I can tell, but it's slightly distracting.

I noticed today when playing that if I right-click my modular armor to open the menu, this error keeps repeating about each second:

Error while running event SmartTrains::Custom Event (ID 109) LuaEquipmentGrid doesn't contain key type. stack traceback:
__SmartTrains__/control.lua:1241: in function <__SmartTrains__/control.lua:1239> [C]: in function 'raise_event'
__SmartTrains__/control.lua:1223: in function <__SmartTrains__/control.lua:1219> [C]: in function 'pcall' __SmartTrains__/control.lua:1219: in [C]: in function 'pcall' __SmartTrains__/control.lua:1219: in function <__SmartTrains__/control.lua:1131>