Fixing broken fixes. Testing.

code/modules/mob/living/carbon/human/life.dm

@@ -228,7 +228,7 @@
 		//END EDIT
 		temperature = max(temperature, 2.7) //There is an occasional bug where the temperature is miscalculated in ares with a small amount of gas on them, so this is necessary to ensure that that bug does not affect this calculation. Space's temperature is 2.7K and most suits that are intended to protect against any cold, protect down to 2.0K.
 	var/thermal_protection_flags = cold ? get_cold_protection_flags(temperature) : get_heat_protection_flags(temperature)
-	var/missing_body_parts_flags = missing_body_parts_flags()
+	var/missing_body_parts_flags = ~get_body_parts_flags()
 	var/max_protection = 1
 	if(missing_body_parts_flags) //I don't like copypasta as much as proc overhead. Do you want me to make these into a macro?
 		DISABLE_BITFIELD(thermal_protection_flags, missing_body_parts_flags)

code/modules/mob/living/carbon/human/species_types/dullahan.dm

@@ -38,13 +38,13 @@
 			head.icon_state = "hardhat1_pumpkin_j"
 			head.custom_head = TRUE
 		head.drop_limb()
-		ENABLE_BITFIELD(head.flags_1, HEAR_1)
-		head.throwforce = 25
-		myhead = new /obj/item/dullahan_relay (head, H)
-		H.put_in_hands(head)
-		var/obj/item/organ/eyes/E = H.getorganslot(ORGAN_SLOT_EYES)
-		for(var/datum/action/item_action/organ_action/OA in E.actions)
-			OA.Trigger()
+		if(!QDELETED(head)) //drop_limb() deletes the limb if it's no drop location and dummy humans used for rendering icons are located in nullspace. Do the math.
+			head.throwforce = 25
+			myhead = new /obj/item/dullahan_relay (head, H)
+			H.put_in_hands(head)
+			var/obj/item/organ/eyes/E = H.getorganslot(ORGAN_SLOT_EYES)
+			for(var/datum/action/item_action/organ_action/OA in E.actions)
+				OA.Trigger()
 
 /datum/species/dullahan/on_species_loss(mob/living/carbon/human/H)
 	ENABLE_BITFIELD(H.flags_1, HEAR_1)
@@ -86,7 +86,7 @@
 /obj/item/organ/tongue/dullahan/handle_speech(datum/source, list/speech_args)
 	if(ishuman(owner))
 		var/mob/living/carbon/human/H = owner
-		if(H.dna.species.id == "dullahan")
+		if(isdullahan(H))
 			var/datum/species/dullahan/D = H.dna.species
 			if(isobj(D.myhead.loc))
 				var/obj/O = D.myhead.loc
@@ -116,7 +116,7 @@
 
 	if(ishuman(owner))
 		var/mob/living/carbon/human/H = owner
-		if(H.dna.species.id == "dullahan")
+		if(isdullahan(H))
 			var/datum/species/dullahan/D = H.dna.species
 			D.update_vision_perspective(H)
 
@@ -140,7 +140,8 @@
 
 /obj/item/dullahan_relay/proc/include_owner(list/processing_list, list/hearers)
 	if(!QDELETED(owner))
-		hearers += owner
+		var/list/new_hearers = hearers //It throws errors on compile about invalid expressions otherwise. And so far components only allow binary return values.
+		new_hearers.Add(owner)
 
 /obj/item/dullahan_relay/process()
 	if(!istype(loc, /obj/item/bodypart/head) || QDELETED(owner))
@@ -150,7 +151,7 @@
 /obj/item/dullahan_relay/Destroy()
 	if(!QDELETED(owner))
 		var/mob/living/carbon/human/H = owner
-		if(H.dna.species.id == "dullahan")
+		if(isdullahan(H))
 			var/datum/species/dullahan/D = H.dna.species
 			D.myhead = null
 			owner.gib()

code/modules/surgery/bodyparts/head.dm

@@ -120,6 +120,8 @@
 	..()
 
 /obj/item/bodypart/head/update_icon_dropped()
+	if(custom_head)
+		return
 	var/list/standing = get_limb_icon(1)
 	if(!standing.len)
 		icon_state = initial(icon_state)//no overlays found, we default back to initial icon.
@@ -130,8 +132,6 @@
 	add_overlay(standing)
 
 /obj/item/bodypart/head/get_limb_icon(dropped)
-	if(custom_head)
-		return
 	cut_overlays()
 	. = ..()
 	if(dropped) //certain overlays only appear when the limb is being detached from its owner.

code/modules/surgery/bodyparts/helpers.dm

@@ -334,7 +334,7 @@
 				S.adjusted = ALT_STYLE
 			H.update_inv_wear_suit()
 
-/mob/living/carbon/proc/missing_body_parts_flags()
+/mob/living/carbon/proc/get_body_parts_flags()
 	for(var/X in bodyparts)
 		var/obj/item/bodypart/L = X
 		switch(L.body_part)