Wow, my :nixos: #NixOS *really* does not want me to use flakes to 

I keep hitting this infamous 

error: attribute 'currentSystem' missing

in pkgs/top-level/impure.nix:17:43

localSystem ? { system = args.system or builtins.currentSystem; }

No example flake works for me. I tried specifying my system = "x86_64-linux" absolutely everywhere but it just doesn't care. 

And then always this weird

error: cached failure of attribute 'nixosConfigurations.yann-desktop-nixos.config'

It's tiring... 🙄