The mod Warmonger (1.1.0) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event Warmonger::on_robot_built_entity (ID 14)
Warmonger/scripts/corrosion.lua:15: attempt to index local 'entity' (a nil value)
stack traceback:
Warmonger/scripts/corrosion.lua:15: in function 'engaging'
Warmonger/control.lua:67: in function <Warmonger/control.lua:66>
This doesn't trigger on the first building, but in the first 30 or so.
I am using a quickstart mod that gives real bots at game start, but this will probably trigger anyway.