Hello, Love the mod. Me and some friends were using it and we encountered the following error which crashed the server.

12655.265 Info AppManagerStates.cpp:1941: Saving finished
13213.471 Error MainLoop.cpp:1284: Exception at tick 2193493: The mod Belt Sorter (0.9.1) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event beltSorter::on_tick (ID 0)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__beltSorter/control/belt-sorter.lua:260: in function 'updateCircuitCondition'
beltSorter/control/belt-sorter.lua:195: in function 'tick'
beltSorter/libs/control/entities.lua:198: in function 'entities_tick'
beltSorter/control.lua:47: in function <beltSorter/control.lua:46>
13213.471 Error ServerMultiplayerManager.cpp:91: MultiplayerManager failed: "The mod Belt Sorter (0.9.1) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event beltSorter::on_tick (ID 0)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__beltSorter/control/belt-sorter.lua:260: in function 'updateCircuitCondition'
beltSorter/control/belt-sorter.lua:195: in function 'tick'
beltSorter/libs/control/entities.lua:198: in function 'entities_tick'
beltSorter/control.lua:47: in function <beltSorter/control.lua:46>"
13213.471 Info ServerMultiplayerManager.cpp:799: updateTick(2193493) changing state from(InGame) to(Failed)
13213.480 Quitting: multiplayer error.