Our dedicated server keep spamming this error. What can be the reason?

function: initialise -- file: TLOUZombies.lua line # 146 | MOD: The Last of Us Infected
ERROR: General , 1694107742899> 16,792,028,529> ExceptionLogger.logException> Exception thrown java.lang.RuntimeException: attempted index: getModData of non-table: null at KahluaThread.tableget line:1689.
ERROR: General , 1694107742899> 16,792,028,529> DebugLogStream.printException> Stack trace:
java.lang.RuntimeException: attempted index: getModData of non-table: null
at se.krka.kahlua.vm.KahluaThread.tableget(KahluaThread.java:1689)
at se.krka.kahlua.vm.KahluaThread.luaMainloop(KahluaThread.java:641)
at se.krka.kahlua.vm.KahluaThread.call(KahluaThread.java:163)
at se.krka.kahlua.vm.KahluaThread.pcall(KahluaThread.java:1980)
at se.krka.kahlua.vm.KahluaThread.pcallvoid(KahluaThread.java:1812)
at se.krka.kahlua.integration.LuaCaller.pcallvoid(LuaCaller.java:66)
at se.krka.kahlua.integration.LuaCaller.protectedCallVoid(LuaCaller.java:139)
at zombie.Lua.Event.trigger(Event.java:64)
at zombie.Lua.LuaEventManager.triggerEvent(LuaEventManager.java:92)
at zombie.gameStates.IngameState.updateInternal(IngameState.java:1624)
at zombie.gameStates.IngameState.update(IngameState.java:1333)
at zombie.network.GameServer.main(GameServer.java:903)
LOG : General , 1694107742899> 16,792,028,529> -----------------------------------------
STACK TRACE
-----------------------------------------
function: initialise -- file: TLOUZombies.lua line # 146 | MOD: The Last of Us Infected
LOG : General , 1694107742995> 16,792,028,625> -------------------------------------------------------------
attempted index: getModData of non-table: null
LOG : General , 1694107742995> 16,792,028,625> -----------------------------------------
STACK TRACE