Prevents vents / scrubbers from making air from walls (#16236)

* Prevents getting free air from walls

* Almost forgot

code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm

@@ -23,6 +23,10 @@
 	if(!node)
 		return 0
 
+	var/turf/T = loc
+	if(T.density) //No, you should not be able to get free air from walls
+		return
+
 	var/datum/gas_mixture/environment = loc.return_air()
 
 	var/pressure_delta = air_contents.return_pressure() - environment.return_pressure()

code/modules/atmospherics/machinery/components/unary_devices/vent_pump.dm

@@ -130,6 +130,9 @@
 	..()
 	if(stat & (NOPOWER|BROKEN))
 		return FALSE
+	var/turf/T = loc
+	if(T.density) //No, you should not be able to get free air from walls
+		return
 	if(!node)
 		on = FALSE
 	//broadcast_status() // from now air alarm/control computer should request update purposely --rastaf0

code/modules/atmospherics/machinery/components/unary_devices/vent_scrubber.dm

@@ -196,6 +196,10 @@
 	if(stat & (NOPOWER|BROKEN))
 		return
 
+	var/turf/T = loc
+	if(T.density) //No, you should not be able to get free air from walls
+		return
+
 	if(!node)
 		on = 0