Merge pull request #11822 from Ccomp5950/fix_mining

Makes the mining asteroid airless again.

code/modules/mining/mine_turfs.dm

@@ -3,6 +3,7 @@
 	name = "impassable rock"
 	icon = 'icons/turf/walls.dmi'
 	icon_state = "rock-dark"
+	blocks_air = 1
 
 /turf/simulated/mineral //wall piece
 	name = "Rock"
@@ -525,4 +526,4 @@
 			else if(istype(R.module_state_3,/obj/item/weapon/storage/bag/ore))
 				attackby(R.module_state_3,R)
 			else
-				return
+				return