check for presence of moreblocks before overriding empty bookshelf

homedecor_3d_extras/init.lua

@@ -56,7 +56,8 @@ minetest.override_item("default:bookshelf", {
 	}
 })
 
-minetest.override_item("moreblocks:empty_bookshelf", {
+if minetest.get_modpath("moreblocks") then
+	minetest.override_item("moreblocks:empty_bookshelf", {
 		drawtype = "nodebox",
 		tiles = {
 			"3dbookshelf_top.png",
@@ -79,4 +80,5 @@ minetest.override_item("moreblocks:empty_bookshelf", {
 				{-0.5, -0.0625, -0.5, 0.5, 0.0625, 0.5}, -- NodeBox6
 			}
 		}
-})
+	})
+end