Formatter with efmls

[marvin-tr-81]

Hello, last couple of days I have been trying to setup a formatter using efmls.

I have added pkgs.vimPlugins.efmls-configs-nvim and pkgs.efm-langserver as seen below.

{ pkgs, ... }:
{
  programs.nixvim = {
    enable = true;
    imports = [
      ./core
      ./plugins
    ];
    defaultEditor = true;
  };
  environment.systemPackages = with pkgs; [
    vimPlugins.efmls-configs-nvim
    efm-langserver
  ];
}

Next, I have configured efmls-configs and lsp as seen below. All functionality of nixd, pyright and texlab seems to be working correctly. I get relevant error messages in nixvim.

{
  plugins.efmls-configs = {
    enable = true;
    setup.python.formatter = ["ruff"];
  };
  plugins.lsp = {
    enable = true;
    lazyLoad.settings.event = [ "BufReadPre" "BufNewFile" ];
    servers = {
      nixd.enable = true; # Nix
      pyright.enable = true; # Python
      texlab.enable = true; # LaTeX

      efm = {
        enable = true; # efm
        filetypes = [
          "python"
        ];
      };
    };
  };
}

I sudo nixos-rebuild test as usual.

In nixvim, I open a random python file and I type the command:

:lua vim.lsp.buf.format() 

and I get the following message back:

[LSP] Format request failed, no matching language servers.

Interestingly, when I try this command in a nix file, I do not get an error but the file is not formatted either.

Clearly, I am missing something but could not figure it out. I would appreciate some directions here.

Thanks in advance.