Fixed holodeck hard dels (#27415)

* Fixed holodeck hard dels, MURDERED VARIABLE COPYING

* air but differently

* Add return type hint

code/ZAS/Turf.dm

@@ -184,6 +184,7 @@
 	return 0
 
 /turf/return_air()
+	RETURN_TYPE(/datum/gas_mixture)
 	//Create gas mixture to hold data for passing
 	var/datum/gas_mixture/unsimulated/GM = new
 

code/__HELPERS/unsorted.dm

@@ -961,22 +961,20 @@ proc/GaussRandRound(var/sigma,var/roundto)
 	var/datum/coords/CR = new(x_pos+C.x_pos,y_pos+C.y_pos,z_pos+C.z_pos)
 	return CR
 
-proc/DuplicateObject(obj/original, var/perfectcopy = 0 , var/sameloc = 0)
-	if(!original)
-		return null
-
-	var/obj/O = null
-
-	if(sameloc)
-		O=new original.type(original.loc)
-	else
-		O=new original.type(locate(0,0,0))
-
-	if(perfectcopy)
-		if((O) && (original))
-			for(var/V in original.vars - variables_not_to_be_copied)
-				O.vars[V] = original.vars[V]
-	return O
+// If you're looking at this proc and thinking "that's exactly what I need!"
+// then you're wrong and you need to take a step back and reconsider.
+/atom/movable/proc/DuplicateObject(var/location)
+	var/atom/movable/duplicate = new src.type(location)
+	duplicate.change_dir(dir)
+	duplicate.plane = plane
+	duplicate.layer = layer
+	duplicate.name = name
+	duplicate.desc = desc
+	duplicate.pixel_x = pixel_x
+	duplicate.pixel_y = pixel_y
+	duplicate.pixel_w = pixel_w
+	duplicate.pixel_z = pixel_z
+	return duplicate
 
 
 /area/proc/copy_contents_to(var/area/A , var/platingRequired = 0 )
@@ -1035,6 +1033,7 @@ proc/DuplicateObject(obj/original, var/perfectcopy = 0 , var/sameloc = 0)
 				var/datum/coords/C_trg = refined_trg[B]
 				if(C_src.x_pos == C_trg.x_pos && C_src.y_pos == C_trg.y_pos)
 
+					var/old_name = T.name
 					var/old_dir1 = T.dir
 					var/old_icon_state1 = T.icon_state
 					var/old_icon1 = T.icon
@@ -1044,10 +1043,13 @@ proc/DuplicateObject(obj/original, var/perfectcopy = 0 , var/sameloc = 0)
 							continue moving
 
 					var/turf/X = B.ChangeTurf(T.type)
+					X.name = old_name
 					X.dir = old_dir1
 					X.icon_state = old_icon_state1
 					X.icon = old_icon1 //Shuttle floors are in shuttle.dmi while the defaults are floors.dmi
 
+					X.return_air().copy_from(T.return_air())
+
 					var/list/objs = new/list()
 					var/list/newobjs = new/list()
 					var/list/mobs = new/list()
@@ -1062,11 +1064,7 @@ proc/DuplicateObject(obj/original, var/perfectcopy = 0 , var/sameloc = 0)
 
 
 					for(var/obj/O in objs)
-						newobjs += DuplicateObject(O , 1)
-
-
-					for(var/obj/O in newobjs)
-						O.forceMove(X)
+						newobjs += O.DuplicateObject(X)
 
 					for(var/mob/M in T)
 
@@ -1075,25 +1073,11 @@ proc/DuplicateObject(obj/original, var/perfectcopy = 0 , var/sameloc = 0)
 						mobs += M
 
 					for(var/mob/M in mobs)
-						newmobs += DuplicateObject(M , 1)
-
-					for(var/mob/M in newmobs)
-						M.forceMove(X)
+						newmobs += M.DuplicateObject(X)
 
 					copiedobjs += newobjs
 					copiedobjs += newmobs
 
-
-
-					for(var/V in T.vars - variables_not_to_be_copied)
-						X.vars[V] = T.vars[V]
-
-//					var/area/AR = X.loc
-
-//					if(AR.dynamic_lighting)
-//						X.opacity = !X.opacity
-//						X.sd_SetOpacity(!X.opacity)			//TODO: rewrite this code so it's not messed by lighting ~Carn
-
 					toupdate += X
 
 					refined_src -= T

code/modules/recycling/conveyor2.dm

@@ -313,6 +313,14 @@
 	</ul>"}
 
 
+/obj/machinery/conveyor/DuplicateObject(var/location)
+	var/obj/machinery/conveyor/duplicate = ..()
+	duplicate.in_reverse = in_reverse
+	duplicate.backwards = backwards
+	duplicate.forwards = forwards
+	duplicate.movedir = movedir
+	return duplicate
+
 /obj/machinery/conveyor/multitool_topic(var/mob/user,var/list/href_list,var/obj/O)
 	. = ..()
 	if(.)