The mod Spawner alert (0.1.4) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event spawner-alert::on_nth_tick(60) spawner-alert/control.lua:74: attempt to index field '?' (a nil value)
stack traceback: spawner-alert/control.lua:74: in function <spawner-alert/control.lua:54>