Revert "Fixes a decade old ZAS issue (#483)" (#516)

This reverts commit 829d7ca.

code/game/machinery/doors/door.dm

@@ -179,26 +179,6 @@
 		spark_system = null
 	return ..()
 
-/obj/machinery/door/zas_update_loc()
-	. = ..()
-	if(!.)
-		return
-
-	var/turf/T = get_turf(src)
-
-	if(density)
-		if(!T.zone || T.zone.invalid)
-			return
-		var/zone/old_zone = T.zone
-		old_zone.remove_turf(T)
-
-		var/datum/gas_mixture/GM = unsafe_return_air()
-		old_zone.air.merge(GM)
-		GM.zero()
-
-	else
-		T.update_air_properties()
-
 /obj/machinery/door/zas_canpass(turf/other)
 	if(QDELETED(src))
 		return AIR_ALLOWED
@@ -268,6 +248,14 @@
 			do_animate("deny")
 		return
 
+/obj/machinery/door/Move()
+	var/turf/T = loc
+	. = ..()
+	if(.)
+		T.zas_update_loc()
+		zas_update_loc()
+
+
 /obj/machinery/door/CanAllowThrough(atom/movable/mover, border_dir)
 	. = ..()
 	if(.)

code/modules/atmospherics/ZAS/Atom.dm

@@ -4,8 +4,6 @@
 
 ///Tells ZAS to mark the tile the atom is in to update.
 /atom/proc/zas_update_loc()
-	if(!SSzas.initialized)
-		return FALSE
 	var/turf/T = get_turf(src)
 	if(T?.simulated)
 		SSzas.mark_for_update(T)

code/modules/atmospherics/ZAS/Debug.dm

@@ -31,7 +31,6 @@ GLOBAL_REAL_VAR(list/zasdbgovl_dirzoneblock) = list(
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	layer = FLY_LAYER
 	vis_flags = NONE
-	appearance_flags = RESET_COLOR | RESET_TRANSFORM | RESET_ALPHA | KEEP_APART
 
 /obj/effect/zasdbg/assigned
 	icon_state = "assigned"

code/modules/atmospherics/ZAS/Turf.dm

@@ -91,7 +91,7 @@
 */
 ///Simple heuristic for determining if removing the turf from it's zone will not partition the zone (A very bad thing).
 /turf/proc/can_safely_remove_from_zone()
-	if(isnull(zone) || zone.invalid)
+	if(isnull(zone))
 		return TRUE
 
 	var/check_dirs

code/modules/atmospherics/ZAS/XGM/xgm_gas_mixture.dm

@@ -1,7 +1,7 @@
 /datum/gas_mixture
 	//Associative list of gas moles.
 	//Gases with 0 moles are not tracked and are pruned by updateValues()
-	var/list/gas
+	var/list/gas = list()
 	//Temperature in Kelvin of this gas mix.
 	var/temperature = 0
 
@@ -13,16 +13,14 @@
 	var/group_multiplier = 1
 
 	//List of active tile overlays for this gas_mixture.  Updated by checkTileGraphic()
-	var/list/graphic
+	var/list/graphic = list()
 	//Cache of gas overlay objects
 	var/list/tile_overlay_cache
 
 /datum/gas_mixture/New(_volume = CELL_VOLUME, _temperature = 0, _group_multiplier = 1)
 	volume = _volume
 	temperature = _temperature
 	group_multiplier = _group_multiplier
-	gas = list()
-	graphic = list()
 
 ///Returns the volume of a specific gas within the entire zone.
 /datum/gas_mixture/proc/getGroupGas(gasid)
@@ -34,12 +32,6 @@
 /datum/gas_mixture/proc/getGroupMoles()
 	return total_moles * group_multiplier
 
-/datum/gas_mixture/proc/zero()
-	gas.Cut()
-	temperature = T0C
-	group_multiplier = 1
-	total_moles = 0
-
 ///Takes a gas string and the amount of moles to adjust by. Calls updateValues() if update isn't 0.
 /datum/gas_mixture/proc/adjustGas(gasid, moles, update = TRUE)
 	if(moles == 0)

code/modules/atmospherics/ZAS/Zone.dm

@@ -168,7 +168,7 @@ Class Procs:
 	atmos_sensitive_contents = null
 	#ifdef ZASDBG
 	for(var/turf/T as anything in contents)
-		if(T.simulated)
+		if(!T.simulated)
 			T.dbg(zasdbgovl_invalid_zone)
 	#endif
 
@@ -183,15 +183,13 @@ Class Procs:
 	for(var/turf/T as anything in contents)
 		if(!T.simulated)
 			continue
-		remove_turf(T)
-		CHECK_TICK
-
-	for(var/turf/T as anything in contents)
-		if(!T.simulated)
-			continue
-
+		T.update_graphic(graphic_remove = air.graphic) //we need to remove the overlays so they're not doubled when the zone is rebuilt
+		#ifdef ZASDBG
+		//T.dbg(invalid_zone)
+		#endif
 		T.needs_air_update = 0 //Reset the marker so that it will be added to the list.
 		SSzas.mark_for_update(T)
+
 		CHECK_TICK
 
 ///Assumes a given gas mixture, dividing it amongst the zone.

code/modules/atmospherics/ZAS/zas_extras/inflatable.dm

@@ -230,26 +230,6 @@
 		return
 	return TryToSwitchState(user)
 
-/obj/machinery/inflatable/door/zas_update_loc()
-	. = ..()
-	if(!.)
-		return
-
-	var/turf/T = get_turf(src)
-
-	if(density)
-		if(!T.zone || T.zone.invalid)
-			return
-		var/zone/old_zone = T.zone
-		old_zone.remove_turf(T)
-
-		var/datum/gas_mixture/GM = unsafe_return_air()
-		old_zone.air.merge(GM)
-		GM.zero()
-
-	else
-		T.update_air_properties()
-
 /obj/structure/inflatable/door/proc/TryToSwitchState(atom/user)
 	if(isSwitchingStates) return
 	if(ismob(user))