properly detect and use sounds from default/mcl

crops/rhubarb.lua

@@ -54,7 +54,7 @@ local def = {
 	},
 	_mcl_hardness = farming.mcl_hardness,
 	is_ground_content = false,
-	sounds = farming.sounds.node_sound_leaves_defaults(),
+	sounds = farming.node_sound_leaves_defaults(),
 	minlight = 10,
 	maxlight = 12
 }