The mod Combat Robot Overhaul (2.1.28) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event CombatRobotsOverhaul::on_nth_tick(60)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'get_closest'
CombatRobotsOverhaul/scripts/destroyergroup.lua:45: in function 'update'
CombatRobotsOverhaul/control.lua:302: in function <CombatRobotsOverhaul/control.lua:295>

Looks like an invalid entity got into the lists of targets. To get rid of this, you can use the command /combatrobotoverhaul-clean-invalid. Unfortunately, I haven't found the cause for the invalid entities yet as this shouldn't happen. Can you tell me on which surface it happened? Or better, have a save?

not sure what you mean by surface but It happened on Nauvis, and i have no idea how to share a save

No worries about the save. The information regarding the surface (Nauvis) is helpful.