Added a "return" that I had forgot

init.lua

@@ -12,6 +12,7 @@ function place_spore(itemstack, placer, pointed_thing, name, topoint, soilblock)
 
 	-- return if any of the nodes is not registered
 	if not minetest.registered_nodes[under.name] then
+		return
 	end
 
 	-- if not protected then add node and remove 1 item from the itemstack