Multiple flaky test failures in omnitools/engiborg, spawn_humans

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Flaky tests were detected in this test run. This means that there was a failure that was cleared when the tests were simply restarted.
Failures:

omnitools/engiborg: [19:06:19] Runtime in code/datums/signals.dm,72: Cannot read null._listen_lookup
proc name: UnregisterSignal (/datum/proc/UnregisterSignal)
src: /datum/status_effect/grabbing (/datum/status_effect/grabbing)
call stack:
/datum/status_effect/grabbing (/datum/status_effect/grabbing): UnregisterSignal(null, /list (/list))
/datum/status_effect/grabbing (/datum/status_effect/grabbing): Destroy(0)
qdel(/datum/status_effect/grabbing (/datum/status_effect/grabbing), 0)
/datum/status_effect/grabbed (/datum/status_effect/grabbed): on remove()
/datum/status_effect/grabbed (/datum/status_effect/grabbed): Destroy(0)
qdel(/datum/status_effect/grabbed (/datum/status_effect/grabbed), 0)
/datum/status_effect/grabbed (/datum/status_effect/grabbed): ungrabbed(the red raptor (/mob/living/basic/raptor/red), the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava))
the red raptor (/mob/living/basic/raptor/red):  SendSignal("movable_no_longer_pulled", /list (/list))
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): stop pulling()
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): stop pulling()
/datum/ai_behavior/run_away_fr... (/datum/ai_behavior/run_away_from_target/lobster): perform(0.1, /datum/ai_controller/basic_con... (/datum/ai_controller/basic_controller/lobstrosity), "BB_basic_current_target", "BB_basic_current_target_hiding...")
/datum/ai_controller/basic_con... (/datum/ai_controller/basic_controller/lobstrosity): ProcessBehavior(0.1, /datum/ai_behavior/run_away_fr... (/datum/ai_behavior/run_away_from_target/lobster))
/datum/ai_controller/basic_con... (/datum/ai_controller/basic_controller/lobstrosity): process(0.1)
AI Behavior Ticker (/datum/controller/subsystem/processing/ai_behaviors): fire(0)
AI Behavior Ticker (/datum/controller/subsystem/processing/ai_behaviors): fire(0)
AI Behavior Ticker (/datum/controller/subsystem/processing/ai_behaviors): ignite(0)
Master (/datum/controller/master): RunQueue()
Master (/datum/controller/master): Loop(4)
Master (/datum/controller/master): StartProcessing(0) at code/datums/signals.dm:72
spawn_humans: [19:07:17] Runtime in code/datums/signals.dm,72: Cannot read null._listen_lookup
proc name: UnregisterSignal (/datum/proc/UnregisterSignal)
usr: *no key*/(chasm lobstrosity)
usr.loc: (Lavaland Wastes (56,48,3))
src: /datum/status_effect/grabbing (/datum/status_effect/grabbing)
call stack:
/datum/status_effect/grabbing (/datum/status_effect/grabbing): UnregisterSignal(null, /list (/list))
/datum/status_effect/grabbing (/datum/status_effect/grabbing): Destroy(0)
qdel(/datum/status_effect/grabbing (/datum/status_effect/grabbing), 0)
/datum/status_effect/grabbed (/datum/status_effect/grabbed): on remove()
/datum/status_effect/grabbed (/datum/status_effect/grabbed): Destroy(0)
qdel(/datum/status_effect/grabbed (/datum/status_effect/grabbed), 0)
/datum/status_effect/grabbed (/datum/status_effect/grabbed): ungrabbed(the red raptor (/mob/living/basic/raptor/red), the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava))
the red raptor (/mob/living/basic/raptor/red):  SendSignal("movable_no_longer_pulled", /list (/list))
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): stop pulling()
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): stop pulling()
...
Lobster Rush (/datum/action/cooldown/mob_cooldown/charge/basic_charge/lobster): on bump(the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava), the rock (57,48,3) (/turf/closed/mineral/random/volcanic))
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): Bump(the rock (57,48,3) (/turf/closed/mineral/random/volcanic))
the rock (57,48,3) (/turf/closed/mineral/random/volcanic): Enter(the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava))
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): Move(the rock (57,48,3) (/turf/closed/mineral/random/volcanic), 4, 0, 1)
the chasm lobstrosity (/mob/living/basic/mining/lobstrosity/lava): Move(the rock (57,47,3) (/turf/closed/mineral/random/volcanic), 6, 0, 1)
/datum/move_loop/has_target/mo... (/datum/move_loop/has_target/move_towards): move()
Movement Loops (/datum/controller/subsystem/movement): pour bucket(/list (/list))
Movement Loops (/datum/controller/subsystem/movement): ignite(0)
Master (/datum/controller/master): Loop(4)
Master (/datum/controller/master): StartProcessing(0) at code/datums/signals.dm:72