As you create more and more content (expecially if as a dev you want to follow best practices) you end up quickly with lot of folders and files.
Actually there is no way to close folders that I’d consider mandatory for a tool like this.
Another thing you could add with very little effort is to allow to “close all tabs”
afaik you are using monaco editor, so you should have everything at hand and you could have a cool editor (I already apprecciate this a lot because of the speed to test out ideas)