Fix crash due to nil value in recipe ingredients

lignumis/data.lua

@@ -22,14 +22,9 @@ Lignumis = {
     lab_blacklist = {
         "wood-lab", -- Lignumis
         "cerys-lab" -- Cerys
-    },
-
-    assets = "__lignumis-assets__/"
+    }
 }
 
-Lignumis.graphics = Lignumis.assets .. "graphics/"
-Lignumis.sound = Lignumis.assets .. "sound/"
-
 if not settings.startup["lignumis-technology-progression"].value then
     Lignumis.science_pack_whitelist = {}
 end