Fix infinite gold ingot / diamond spawning

mods/tutorial/init.lua

@@ -1181,6 +1181,10 @@ minetest.register_node("tutorial:itemspawner", {
 
 		local offset = minetest.string_to_pos(meta:get_string("offset"))
 		local itemstring = meta:get_string("itemstring")
+		local alias = minetest.registered_aliases[itemstring]
+		if alias then
+			itemstring = alias
+		end
 		local x, y, z = offset.x, offset.y, offset.z
 		local spawnpos = {x=pos.x+x, y=pos.y+y, z=pos.z+z}
 		local objs = minetest.get_objects_inside_radius(spawnpos, 1)