Fix resin doors not closing on mob/living if they are merged with wee…

…ds (#4990)

# About the pull request

This PR simply changes the mob/living check in
`/obj/structure/mineral_door/resin/Close()` to also account for whether
they are merged with the weeds. As soon as xeno corpses are also merging
with weeds this will handle them too.

# Explain why it's good for the game

Although I think this is a very rare situation, it can be especially
confusing if a fully weeded corpse that intentionally is hard to see is
causing a door to not close (seemingly arbitrarily).

# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>


https://github.com/cmss13-devs/cmss13/assets/76988376/4770ff65-c484-4e88-9381-19dfad22ffae

</details>


# Changelog
:cl: Drathek
fix: Resin doors will now close on dead mobs that are merged with weeds
(currently only human).
fix: Resin doors will now restart their closing timer each open making
the delay to close consistent.
code: Added a TRAIT_MERGED_WITH_WEEDS that is set whenever the mob is
currently merged with weeds.
/:cl:

code/__DEFINES/traits.dm

@@ -147,6 +147,8 @@
 #define TRAIT_IMMOBILIZED "immobilized"
 /// Apply this to make a mob not dense, and remove it when you want it to no longer make them undense, other sorces of undesity will still apply. Always define a unique source when adding a new instance of this!
 #define TRAIT_UNDENSE "undense"
+/// Apply this to identify a mob as merged with weeds
+#define TRAIT_MERGED_WITH_WEEDS "merged_with_weeds"
 
 // SPECIES TRAITS
 /// Knowledge of Yautja technology

code/datums/components/weed_food.dm

@@ -260,6 +260,7 @@
 	merged = TRUE
 
 	ADD_TRAIT(parent_mob, TRAIT_UNDENSE, XENO_WEED_TRAIT)
+	ADD_TRAIT(parent_mob, TRAIT_MERGED_WITH_WEEDS, XENO_WEED_TRAIT)
 	parent_mob.anchored = TRUE
 	parent_mob.mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	parent_mob.plane = FLOOR_PLANE
@@ -288,6 +289,7 @@
 		UnregisterSignal(absorbing_weeds, COMSIG_PARENT_QDELETING)
 	absorbing_weeds = null
 
+	REMOVE_TRAIT(parent_mob, TRAIT_MERGED_WITH_WEEDS, XENO_WEED_TRAIT)
 	parent_mob.anchored = FALSE
 	parent_mob.mouse_opacity = MOUSE_OPACITY_ICON
 	parent_mob.plane = GAME_PLANE

code/modules/cm_aliens/XenoStructures.dm

@@ -418,18 +418,23 @@
 	update_icon()
 	isSwitchingStates = 0
 	layer = DOOR_OPEN_LAYER
-	spawn(close_delay)
-		if(!isSwitchingStates && state == 1)
-			Close()
+	addtimer(CALLBACK(src, PROC_REF(Close)), close_delay, TIMER_UNIQUE|TIMER_OVERRIDE)
+
+/obj/structure/mineral_door/resin/proc/close_blocked()
+	for(var/turf/turf in locs)
+		for(var/mob/living/living_mob in turf)
+			if(!HAS_TRAIT(living_mob, TRAIT_MERGED_WITH_WEEDS))
+				return TRUE
+	return FALSE
 
 /obj/structure/mineral_door/resin/Close()
-	if(!state || !loc) return //already closed
+	if(!state || !loc || isSwitchingStates)
+		return //already closed or changing
 	//Can't close if someone is blocking it
-	for(var/turf/turf in locs)
-		if(locate(/mob/living) in turf)
-			spawn (close_delay)
-				Close()
-			return
+	if(close_blocked())
+		addtimer(CALLBACK(src, PROC_REF(Close)), close_delay, TIMER_UNIQUE|TIMER_OVERRIDE)
+		return
+
 	isSwitchingStates = 1
 	playsound(loc, "alien_resin_move", 25)
 	flick("[mineralType]closing",src)
@@ -440,10 +445,10 @@
 	update_icon()
 	isSwitchingStates = 0
 	layer = DOOR_CLOSED_LAYER
-	for(var/turf/turf in locs)
-		if(locate(/mob/living) in turf)
-			Open()
-			return
+
+	if(close_blocked())
+		Open()
+		return
 
 /obj/structure/mineral_door/resin/Dismantle(devastated = 0)
 	qdel(src)