Fix flaky hard delete related to wound-induced brain traumas (#90751)

## About The Pull Request

Brain traumas caused by head wounds are stored as a reference on the
wound, but certain brain traumas (like split personality) `qdel`
themselves in `on_gain()` if conditions aren't valid for them to exist,
`/obj/item/organ/brain/proc/brain_gain_trauma` returns a reference even
if this happens, leading to the ref being stored on the wound and
preventing the trauma from being fully deleted.

## Why It's Good For The Game

Fixes #87752 

## Changelog

No player facing changes

---------

Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>

code/datums/brain_damage/brain_trauma.dm

@@ -42,6 +42,7 @@
 		to_chat(owner, gain_text)
 	RegisterSignal(owner, COMSIG_MOB_SAY, PROC_REF(handle_speech))
 	RegisterSignal(owner, COMSIG_MOVABLE_HEAR, PROC_REF(handle_hearing))
+	return TRUE
 
 //Called when removed from a mob
 /datum/brain_trauma/proc/on_lose(silent)

code/datums/brain_damage/creepy_trauma.dm

@@ -22,14 +22,13 @@
 		obsession = find_obsession()
 		if(!obsession)//we didn't find one
 			lose_text = ""
-			qdel(src)
-			return
+			return FALSE
 	gain_text = span_warning("You hear a sickening, raspy voice in your head. It wants one small task of you...")
 	owner.mind.add_antag_datum(/datum/antagonist/obsessed)
 	antagonist = owner.mind.has_antag_datum(/datum/antagonist/obsessed)
 	antagonist.trauma = src
 	RegisterSignal(obsession, COMSIG_MOB_EYECONTACT, PROC_REF(stare))
-	..()
+	. = ..()
 	//antag stuff//
 	antagonist.forge_objectives(obsession.mind)
 	antagonist.greet()

code/datums/brain_damage/hypnosis.dm

@@ -47,7 +47,7 @@
 	antagonist.objectives = list(fixation)
 
 	hypno_alert.desc = "\"[hypnotic_phrase]\"... your mind seems to be fixated on this concept."
-	..()
+	. = ..()
 
 /datum/brain_trauma/hypnosis/on_lose()
 	message_admins("[ADMIN_LOOKUPFLW(owner)] is no longer hypnotized with the phrase '[hypnotic_phrase]'.")

code/datums/brain_damage/imaginary_friend.dm

@@ -15,9 +15,8 @@
 /datum/brain_trauma/special/imaginary_friend/on_gain()
 	var/mob/living/M = owner
 	if(M.stat == DEAD || !M.client)
-		qdel(src)
-		return
-	..()
+		return FALSE
+	. = ..()
 	make_friend()
 	get_ghost()
 

code/datums/brain_damage/magic.dm

@@ -62,7 +62,7 @@
 
 /datum/brain_trauma/magic/antimagic/on_gain()
 	ADD_TRAIT(owner, TRAIT_ANTIMAGIC, TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/magic/antimagic/on_lose()
 	REMOVE_TRAIT(owner, TRAIT_ANTIMAGIC, TRAUMA_TRAIT)

code/datums/brain_damage/mild.dm

@@ -79,7 +79,7 @@
 
 /datum/brain_trauma/mild/speech_impediment/on_gain()
 	ADD_TRAIT(owner, TRAIT_UNINTELLIGIBLE_SPEECH, TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/mild/speech_impediment/on_lose()
 	REMOVE_TRAIT(owner, TRAIT_UNINTELLIGIBLE_SPEECH, TRAUMA_TRAIT)
@@ -167,7 +167,7 @@
 
 /datum/brain_trauma/mild/muscle_spasms/on_gain()
 	owner.apply_status_effect(/datum/status_effect/spasms)
-	..()
+	. = ..()
 
 /datum/brain_trauma/mild/muscle_spasms/on_lose()
 	owner.remove_status_effect(/datum/status_effect/spasms)

code/datums/brain_damage/severe.dm

@@ -15,7 +15,7 @@
 
 /datum/brain_trauma/severe/mute/on_gain()
 	ADD_TRAIT(owner, TRAIT_MUTE, TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/severe/mute/on_lose()
 	REMOVE_TRAIT(owner, TRAIT_MUTE, TRAUMA_TRAIT)
@@ -31,7 +31,7 @@
 /datum/brain_trauma/severe/aphasia/on_gain()
 	owner.add_blocked_language(subtypesof(/datum/language) - /datum/language/aphasia, LANGUAGE_APHASIA)
 	owner.grant_language(/datum/language/aphasia, source = LANGUAGE_APHASIA)
-	..()
+	. = ..()
 
 /datum/brain_trauma/severe/aphasia/on_lose()
 	if(!QDELING(owner))
@@ -49,7 +49,7 @@
 
 /datum/brain_trauma/severe/blindness/on_gain()
 	owner.become_blind(TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/severe/blindness/on_lose()
 	owner.cure_blind(TRAUMA_TRAIT)
@@ -104,7 +104,7 @@
 	lose_text = span_notice("You can feel [subject] again!")
 
 /datum/brain_trauma/severe/paralysis/on_gain()
-	..()
+	. = ..()
 	for(var/X in paralysis_traits)
 		ADD_TRAIT(owner, X, TRAUMA_TRAIT)
 
@@ -196,7 +196,7 @@
 
 /datum/brain_trauma/severe/pacifism/on_gain()
 	ADD_TRAIT(owner, TRAIT_PACIFISM, TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/severe/pacifism/on_lose()
 	REMOVE_TRAIT(owner, TRAIT_PACIFISM, TRAUMA_TRAIT)
@@ -259,7 +259,7 @@
 
 /datum/brain_trauma/severe/dyslexia/on_gain()
 	ADD_TRAIT(owner, TRAIT_ILLITERATE, TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/severe/dyslexia/on_lose()
 	REMOVE_TRAIT(owner, TRAIT_ILLITERATE, TRAUMA_TRAIT)

code/datums/brain_damage/special.dm

@@ -25,7 +25,7 @@
 
 /datum/brain_trauma/special/godwoken/on_gain()
 	ADD_TRAIT(owner, TRAIT_HOLY, TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/special/godwoken/on_lose()
 	REMOVE_TRAIT(owner, TRAIT_HOLY, TRAUMA_TRAIT)
@@ -266,7 +266,7 @@
 
 /datum/brain_trauma/special/tenacity/on_gain()
 	owner.add_traits(list(TRAIT_NOSOFTCRIT, TRAIT_NOHARDCRIT, TRAIT_ANALGESIA), TRAUMA_TRAIT)
-	..()
+	. = ..()
 
 /datum/brain_trauma/special/tenacity/on_lose()
 	owner.remove_traits(list(TRAIT_NOSOFTCRIT, TRAIT_NOHARDCRIT, TRAIT_ANALGESIA), TRAUMA_TRAIT)
@@ -463,7 +463,7 @@
 	owner.add_mood_event("combat_ptsd", /datum/mood_event/desentized)
 	owner.mob_mood?.mood_modifier -= 1 //Basically nothing can change your mood
 	owner.mob_mood?.sanity_level = SANITY_DISTURBED //Makes sanity on a unstable level unless cured
-	..()
+	. = ..()
 
 /datum/brain_trauma/special/ptsd/on_lose()
 	owner.clear_mood_event("combat_ptsd")

code/datums/brain_damage/split_personality.dm

@@ -17,9 +17,8 @@
 /datum/brain_trauma/severe/split_personality/on_gain()
 	var/mob/living/brain_owner = owner
 	if(brain_owner.stat == DEAD || !GET_CLIENT(brain_owner)) //No use assigning people to a corpse or braindead
-		qdel(src)
-		return
-	..()
+		return FALSE
+	. = ..()
 	make_backseats()
 
 #ifdef UNIT_TESTS
@@ -209,7 +208,7 @@
 			| strings("ion_laws.json", "iondrinks"))
 
 /datum/brain_trauma/severe/split_personality/brainwashing/on_gain()
-	..()
+	. = ..()
 	var/mob/living/split_personality/traitor/traitor_backseat = stranger_backseat
 	traitor_backseat.codeword = codeword
 	traitor_backseat.objective = objective

code/modules/mob/living/brain/brain_item.dm

@@ -98,7 +98,8 @@
 			continue
 
 		trauma.owner = brain_owner
-		trauma.on_gain()
+		if(!trauma.on_gain())
+			qdel(trauma)
 
 	//Update the body's icon so it doesnt appear debrained anymore
 	if(!special && !(brain_owner.living_flags & STOP_OVERLAY_UPDATE_BODY_PARTS))
@@ -582,7 +583,9 @@
 		if(SEND_SIGNAL(owner, COMSIG_CARBON_GAIN_TRAUMA, trauma, resilience) & COMSIG_CARBON_BLOCK_TRAUMA)
 			qdel(actual_trauma)
 			return FALSE
-		actual_trauma.on_gain()
+		if(!actual_trauma.on_gain())
+			qdel(actual_trauma)
+			return FALSE
 		log_game("[key_name_and_tag(owner)] has gained the following brain trauma: [trauma.type]")
 	if(resilience)
 		actual_trauma.resilience = resilience