Fix remaining non-returning Destroys()

Plus a little refactor to mining flaps and spacepod doors- they now use
CanAtmosPass instead of manually setting the turf to no-atmos-passing

code/game/objects/effects/effect_system.dm

@@ -1079,10 +1079,9 @@ steam.start() -- spawns the effect
 		air_update_turf(1)
 
 	Destroy()
-
 		density = 0
 		air_update_turf(1)
-		..()
+		return ..()
 
 	Move()
 		var/turf/T = loc