The mod Rampant, fixed (1.7.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event RampantFixed::on_entity_died (ID 4)
Attack target has no health.
stack traceback:
[C]:in function 'set_multi_command'
RampantFixed/libs/SquadDefense.lua:109:in function 'retreatUnits'
RampantFixed/control.lua:708:in function
<RampantFixed/control.lua:645>

As far as I know, this is a factorio bug before version 1.1.81
https://forums.factorio.com/viewtopic.php?f=3&t=105959

"Fixed a crash when unit has a composite command with a dead unit group. (105935)"

What version do you have?

Also, it confuses me that the biter tries to attack the target without health (such targets are invulnerable). Guess I need your save

Hi, I just encountered same error as above on 1.1.89. Unfortunately I tried but couldn't reproduce it, but at the time I was in editor extensions with a 3 biter nests placed down and a couple of biters were around it, I was testing bio land mine launcher ammo from rampant arsenal fired from light artillery from a distance. Several shots were fired without an error and biters were going to attack it / attacking it, then on one of the shots that error appeared. I think (not sure) error happened on mine detonation, but as I said I couldn't reproduce it. Maybe the description helps.

Okay, doesn't seem to be related to land mines. Save: https://easyupload.io/z0iwsz

Just run down inside turret walls immediately and let turrets shoot. Reload and try again if no error, errors 80% of time for me.

Thank you. I'll see what's up

Thanks for the great example
Looks like we've found a factorio bug. If you give a command to the biters when they die at the same time, then there will be an error.
Until fixed, biters will not try to escape on mass death - this removes the error

Glad you found it. I'd been pulling my hair out trying to reproduce.