223418.614 Info ServerMultiplayerManager.cpp:948: updateTick(215300090) received stateChanged peerID(41) oldState(ConnectedLoadingMap) newState(TryingToCatchUp)
223424.313 Info ServerMultiplayerManager.cpp:948: updateTick(215300090) received stateChanged peerID(41) oldState(TryingToCatchUp) newState(WaitingForCommandToStartSendingTickClosures)
223424.392 Info ServerMultiplayerManager.cpp:948: updateTick(215300090) received stateChanged peerID(41) oldState(WaitingForCommandToStartSendingTickClosures) newState(InGame)
223424.942 Info GameActionHandler.cpp:5076: UpdateTick (215300090) processed PlayerJoinGame peerID(41) playerIndex(10) mode(connect)
223534.509 Script @LogisticTrainNetwork/script/surface-interface.lua:85: Removing LTN stops and surface connections on surface [43].
223621.111 Script @LogisticTrainNetwork/script/surface-interface.lua:85: Removing LTN stops and surface connections on surface [49].
223681.986 Script @space-exploration/scripts/zone.lua:450: Zone.apply_controls_to_mapgen: Attempt to apply invalid control name to mapgen: tree
223686.115 Script @LogisticTrainNetwork/script/surface-interface.lua:85: Removing LTN stops and surface connections on surface [49].
223728.091 Script @LogisticTrainNetwork/script/surface-interface.lua:85: Removing LTN stops and surface connections on surface [49].
223996.449 Script @LogisticTrainNetwork/script/surface-interface.lua:85: Removing LTN stops and surface connections on surface [43].
224210.000 Error MainLoop.cpp:1288: Exception at tick 215336302: The mod LTN Combinator Modernized (1.0.14) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_click (ID 1)
LTN_Combinator_Modernized/script/gui.lua:365: attempt to index field 'signal' (a nil value)
stack traceback:
LTN_Combinator_Modernized/script/gui.lua:365: in function 'handler'
LTN_Combinator_Modernized/lib/gui.lua:390: in function <LTN_Combinator_Modernized/lib/gui.lua:376>
224210.001 Error ServerMultiplayerManager.cpp:92: MultiplayerManager failed: "The mod LTN Combinator Modernized (1.0.14) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_click (ID 1)
LTN_Combinator_Modernized/script/gui.lua:365: attempt to index field 'signal' (a nil value)
stack traceback:
LTN_Combinator_Modernized/script/gui.lua:365: in function 'handler'
LTN_Combinator_Modernized/lib/gui.lua:390: in function <LTN_Combinator_Modernized/lib/gui.lua:376>"
224210.001 Info ServerMultiplayerManager.cpp:797: updateTick(215336302) changing state from(InGame) to(Failed)
224210.001 Quitting: multiplayer error.
224218.519 Info ServerMultiplayerManager.cpp:141: Quitting multiplayer connection.
224218.519 Info ServerMultiplayerManager.cpp:797: updateTick(4294967295) changing state from(Failed) to(Closed)
224218.632 Info HttpSharedState.cpp:54: Downloading https://multiplayer.factorio.com/remove-game/15033332
224218.917 Info UDPSocket.cpp:218: Closing socket
224218.917 Info UDPSocket.cpp:248: Socket closed
224218.918 Info UDPSocket.cpp:218: Closing socket
224219.417 Info UDPSocket.cpp:218: Closing socket
224219.418 Info UDPSocket.cpp:248: Socket closed
224219.422 Goodbye

According to the players on my server, they were doing nothing when the server crashed, twice.
If you need more information, do tell me where I should look for it.

Do you have a world file available that was causing this?

Do you have a world file available that was causing this?
Yes, I do.
https://drive.google.com/file/d/1sLew240dX5gWWmAv-MifFX6cNVpqiGTR/view?usp=sharing

I think I may have a decent idea what happend. However, I just released a full rewrite of the mod that should eliminate the class of crashes this fell under. But, I'm also sure I've introduced a few new bugs. :) Give it a try and please let me know. I'll address everything new as quickly as I can.

Great! Will try harder :)