Fixes resin stacking & allows lasers to pass through resin (#28842)

* Fixes resin stacking
Lets you shoot through Resin with lasers!

* Small code cleanup

* TRUE

code/game/objects/effects/effect_system/effects_foam.dm

@@ -276,6 +276,10 @@
 		for(var/obj/item/Item in O)
 			Item.extinguish()
 
+/obj/structure/foamedmetal/resin/CanPass(atom/movable/mover, turf/target, height)
+	if(istype(mover) && mover.checkpass(PASSGLASS))
+		return TRUE
+	. = ..()
 
 #undef ALUMINUM_FOAM
 #undef IRON_FOAM

code/game/objects/items/weapons/tanks/watertank.dm

@@ -295,6 +295,10 @@
 	if(nozzle_mode == RESIN_FOAM)
 		if(!Adj|| !isturf(target))
 			return
+		for(var/S in target)
+			if(istype(S, /obj/effect/particle_effect/foam/metal/resin) || istype(S, /obj/structure/foamedmetal/resin))
+				to_chat(user, "<span class='warning'>There's already resin here!</span>")
+				return
 		if(metal_synthesis_cooldown < 5)
 			var/obj/effect/particle_effect/foam/metal/resin/F = new (get_turf(target))
 			F.amount = 0