Fix errors caused by right-clicking unknown nodes

init.lua

@@ -106,9 +106,15 @@ if lavastuff.enable_tool_fire == true and lavastuff.fire_node then
 	function lavastuff.tool_fire_func(itemstack, user, pointed)
 		local name = user:get_player_name()
 
-		if pointed.type == "node" then
+		if pointed.type ~= "node" then
+			return
+		end
+
 		local node = minetest.get_node(pointed.under)
 		local def = minetest.registered_nodes[node.name]
+		if not def then
+			return -- Unknown node
+		end
 
 		if def.on_rightclick then
 			return def.on_rightclick(pointed.under, node, user, itemstack, pointed)
@@ -122,7 +128,6 @@ if lavastuff.enable_tool_fire == true and lavastuff.fire_node then
 			COOLDOWN:set(user, 1)
 		end
 	end
-	end
 end
 
 function lavastuff.burn_drops(tool)

items/nodecore.lua

@@ -74,6 +74,9 @@ minetest.override_item("lavastuff:shovel", {
 
 		local node = minetest.get_node(pointed_thing.under)
 		local def = minetest.registered_nodes[node.name]
+		if not def then
+			return -- Unknown node
+		end
 
 		if not cooldown:get(user) and (def.groups.sand or (def.groups.silica_molten and def.liquidtype == "source")) then
 			cooldown:set(user, 0)