FYI, the Blueprint Sandbox mod will change players' force each time the play enter or leave the lab.

21503.593 Script @blueprint-sandboxes/scripts/illusion.lua:191: Replaced 0 entities in Sandbox Blueprint
21507.293 Script @blueprint-sandboxes/scripts/illusion.lua:191: Replaced 0 entities in Sandbox Blueprint
21510.295 Error MainLoop.cpp:1432: Exception at tick 4456800: The mod Auto-Switch Techs (1.3.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event AutoSwitchTechs::on_nth_tick(600)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__AutoSwitchTechs/control.lua:158: in function 'getLabSciencesAvailable'
AutoSwitchTechs/control.lua:323: in function 'updateResearchQueueForForce'
AutoSwitchTechs/control.lua:366: in function <AutoSwitchTechs/control.lua:361>
21510.295 Error ServerMultiplayerManager.cpp:84: MultiplayerManager failed: "The mod Auto-Switch Techs (1.3.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event AutoSwitchTechs::on_nth_tick(600)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__AutoSwitchTechs/control.lua:158: in function 'getLabSciencesAvailable'
AutoSwitchTechs/control.lua:323: in function 'updateResearchQueueForForce'
AutoSwitchTechs/control.lua:366: in function <AutoSwitchTechs/control.lua:361>"
21510.295 Info ServerMultiplayerManager.cpp:806: updateTick(4456800) changing state from(InGame) to(Failed)
21510.309 Quitting: multiplayer error.

I posted a new version that should fix this.

I tried in multiplayer with Blueprint Sandbox mod and I couldn't actually make it crash like your log, but I think this version will fix it and probably prevents crashes with other mods as well.

Cool, thank you!