Ensures some ling ability icon always update correctly, Fixes a potential input stall in Revival Stasis (#73616)

## About The Pull Request

- For Fleshmend, on apply kinda happens before alerts are made, so using
Fleshmend when you're on fire wouldn't make the alert the "you're on
fire" alert.

- For Revival Stasis, I think I just missed an update call? Which made
it not update on occasion.
- I also patched a potential issue with input stalling on Revival Stasis
while here.

## Changelog

🆑 Melbert
fix: Using Fleshmend while on fire gives the "on fire" fleshmend icon. 
fix: Using Revival stasis more accurately updates the icon where
relevant
fix: Fixes a potential input stall with revival stasis
/🆑

code/datums/status_effects/buffs.dm

@@ -158,6 +158,13 @@
 	RegisterSignal(owner, COMSIG_LIVING_IGNITED, PROC_REF(on_ignited))
 	RegisterSignal(owner, COMSIG_LIVING_EXTINGUISHED, PROC_REF(on_extinguished))
 
+/datum/status_effect/fleshmend/on_creation(mob/living/new_owner, ...)
+	. = ..()
+	if(!. || !owner || !linked_alert)
+		return
+	if(owner.on_fire)
+		linked_alert.icon_state = "fleshmend_fire"
+
 /datum/status_effect/fleshmend/on_remove()
 	UnregisterSignal(owner, list(COMSIG_LIVING_IGNITED, COMSIG_LIVING_EXTINGUISHED))
 

code/modules/antagonists/changeling/changeling_power.dm

@@ -82,7 +82,7 @@ the same goes for Remove(). if you override Remove(), call parent or else your p
 	if(req_stat < user.stat)
 		user.balloon_alert(user, "incapacitated!")
 		return FALSE
-	if((HAS_TRAIT(user, TRAIT_DEATHCOMA)) && (!ignores_fakedeath))
+	if(HAS_TRAIT(user, TRAIT_DEATHCOMA) && !ignores_fakedeath)
 		user.balloon_alert(user, "playing dead!")
 		return FALSE
 	return TRUE

code/modules/antagonists/changeling/powers/fakedeath.dm

@@ -20,7 +20,7 @@
 		build_all_button_icons(UPDATE_BUTTON_NAME|UPDATE_BUTTON_ICON)
 	else
 		to_chat(user, span_notice("We begin our stasis, preparing energy to arise once more."))
-		user.fakedeath("changeling") //play dead
+		user.fakedeath(CHANGELING_TRAIT) //play dead
 		addtimer(CALLBACK(src, PROC_REF(ready_to_regenerate), user), LING_FAKEDEATH_TIME, TIMER_UNIQUE)
 	return TRUE
 
@@ -28,7 +28,7 @@
 	if(!istype(user))
 		return
 
-	user.cure_fakedeath("changeling")
+	user.cure_fakedeath(CHANGELING_TRAIT)
 	// Heal all damage and some minor afflictions,
 	var/flags_to_heal = (HEAL_DAMAGE|HEAL_BODY|HEAL_STATUS|HEAL_CC_STATUS)
 	// but leave out limbs so we can do it specially
@@ -57,20 +57,31 @@
 		return
 
 	to_chat(user, span_notice("We are ready to revive."))
-	build_all_button_icons(UPDATE_BUTTON_NAME|UPDATE_BUTTON_ICON)
 	chemical_cost = 0
 	revive_ready = TRUE
+	build_all_button_icons(UPDATE_BUTTON_NAME|UPDATE_BUTTON_ICON)
 
 /datum/action/changeling/fakedeath/can_sting(mob/living/user)
-	if(HAS_TRAIT_FROM(user, TRAIT_DEATHCOMA, "changeling") && !revive_ready)
-		user.balloon_alert(user, "already reviving!")
+	if(revive_ready)
+		return ..()
+
+	if(!can_enter_stasis(user))
 		return
-	if(!user.stat && !revive_ready) //Confirmation for living changelings if they want to fake their death
-		switch(tgui_alert(usr,"Are we sure we wish to fake our own death?", "Feign Death", list("Yes", "No")))
-			if("No")
-				return
+	//Confirmation for living changelings if they want to fake their death
+	if(user.stat != DEAD)
+		if(tgui_alert(user, "Are we sure we wish to fake our own death?", "Feign Death", list("Yes", "No")) != "Yes")
+			return
+		if(QDELETED(user) || QDELETED(src) || !can_enter_stasis(user))
+			return
+
 	return ..()
 
+/datum/action/changeling/fakedeath/proc/can_enter_stasis(mob/living/user)
+	if(HAS_TRAIT_FROM(user, TRAIT_DEATHCOMA, CHANGELING_TRAIT))
+		user.balloon_alert(user, "already reviving!")
+		return FALSE
+	return TRUE
+
 /datum/action/changeling/fakedeath/update_button_name(atom/movable/screen/movable/action_button/button, force)
 	if(revive_ready)
 		name = "Revive"