Give a better error message when a flake path is not a directory
Give a better error message when a flake path is not a directory

NixOS/nix,NixOS/nix,NixOS/nix,rycee/nix,NixOS/nix,NixOS/nix,rycee/nix,rycee/nix,rycee/nix,rycee/nix