Cause unknown, played through the game perfectly fine the entire time, saved it out and left. turned it on the next day and got this error immediately on load.

LUA ERROR stack traceback:
../mods/workshop-572470943/scripts/prefabs/summons/summonjarvi.lua:78 in (method) OnLoad (Lua) <77-108>
scripts/entityscript.lua:1596 in (method) SetPersistData (Lua) <1581-1598>
scripts/mainfunctions.lua:356 in (global) SpawnSaveRecord (Lua) <321-363>
scripts/gamelogic.lua:552 in (upvalue) PopulateWorld (Lua) <326-586>
scripts/gamelogic.lua:802 in (upvalue) DoInitGame (Lua) <685-881>
scripts/gamelogic.lua:915 in (local) cb (Lua) <909-916>
scripts/saveindex.lua:312 in (upvalue) OnLoadSaveDataFile (Lua) <294-313>
scripts/saveindex.lua:327 in () ? (Lua) <326-328>