Yeah that is an issue not having a final score yet :p but i'll figure out how to, i think i'll only work on the failstate once i manage to finalise the scoring system ^^
Here is a very good, short video about saving the score. When I started using Godot, I learned almost everything from this channel. Even though these videos are for Godot 2, I still recommend to watch the whole playlist, there are many good things in them about game development in general.