check node validity before loading

src/Main.gd

@@ -59,7 +59,10 @@ func load_game():
 
 		# Call the node's save function
 		var node = get_node(node_data["path"])
-		node.call("load", node_data)
+		if node != null:
+			node.call("load", node_data)
+		else:
+			print("Cannot load node ", node_data["path"])
 
 	save_game.close()