Porting some cargo/vending updates.

code/game/machinery/doors/airlock.dm

@@ -413,8 +413,8 @@
 // shock user with probability prb (if all connections & power are working)
 // returns TRUE if shocked, FALSE otherwise
 // The preceding comment was borrowed from the grille's shock script
-/obj/machinery/door/airlock/proc/shock(mob/user, prb)
-	if(!hasPower())		// unpowered, no shock
+/obj/machinery/door/airlock/proc/shock(mob/living/user, prb)
+	if(!istype(user) || !hasPower())		// unpowered, no shock
 		return FALSE
 	if(shockCooldown > world.time)
 		return FALSE	//Already shocked someone recently?