fix(neovim): guard NixOS module to Linux for nix-darwin compatibility 🔧

- wrap Neovim module in `lib.mkIf pkgs.stdenv.isLinux` (no-op on macOS)
- add `lib` to module args
- fix Lua message var: use `config_file` instead of undefined `file`
- keep existing plugins and customRC on Linux unchanged

nixos/neovim.nix

@@ -1,82 +1,85 @@
-{ config, pkgs, ... }:
+{ lib, config, pkgs, ... }:
 
 {
-  programs.neovim = {
-    enable = true;
-    defaultEditor = true;
-    configure = {
-      customRC = ''
-        set title
-        set go=a
-        set mouse=a
-        set nohlsearch
-        set number
-        let mapleader=","
+  # Only apply the Neovim NixOS module options on Linux.
+  config = lib.mkIf pkgs.stdenv.isLinux {
+    programs.neovim = {
+      enable = true;
+      defaultEditor = true;
 
-        lua << EOF
-          local config_file = os.getenv("HOME")..'/.local/share/nvim_color_scheme'
-          local f=io.open(config_file, "r")
-          if f~=nil then 
-              local system_theme = f:read()
-              -- f:close()
-              io.close(f)
-              if system_theme == 'dark' then
-                  vim.cmd("set bg=dark")
-              elseif system_theme == 'light' then
-                  vim.cmd("set bg=light")
-              else
-                  print('warning: expected value "light" or "dark"')
-                  print('  got:', system_theme)
-                  print('  expected path:', file)
-              end
-          else 
-              print('warning: nvim color scheme not found')
-              print('  expected path:', file)
-          end
-        EOF
+      configure = {
+        customRC = ''
+          set title
+          set go=a
+          set mouse=a
+          set nohlsearch
+          set number
+          let mapleader=","
 
-        colorscheme catppuccin " catppuccin-latte, catppuccin-frappe, catppuccin-macchiato, catppuccin-mocha
+          lua << EOF
+            local config_file = os.getenv("HOME")..'/.local/share/nvim_color_scheme'
+            local f = io.open(config_file, "r")
+            if f ~= nil then
+                local system_theme = f:read()
+                io.close(f)
+                if system_theme == 'dark' then
+                    vim.cmd("set bg=dark")
+                elseif system_theme == 'light' then
+                    vim.cmd("set bg=light")
+                else
+                    print('warning: expected value "light" or "dark"')
+                    print('  got:', system_theme)
+                    print('  expected path:', config_file)
+                end
+            else
+                print('warning: nvim color scheme not found')
+                print('  expected path:', config_file)
+            end
+          EOF
 
-        " netrw (dir listing) settings
-        let g:netrw_liststyle = 3
-        let g:netrw_banner = 0
-        let g:netrw_browse_split = 3
-        let g:netrw_winsize = 25  " % of page
+          colorscheme catppuccin " catppuccin-latte, catppuccin-frappe, catppuccin-macchiato, catppuccin-mocha
 
-        set listchars=tab:→\ ,space:·,nbsp:␣,trail:•,eol:¶,precedes:«,extends:»
-        set clipboard+=unnamedplus
+          " netrw (dir listing) settings
+          let g:netrw_liststyle = 3
+          let g:netrw_banner = 0
+          let g:netrw_browse_split = 3
+          let g:netrw_winsize = 25  " % of page
 
-        " Replace-all is aliased to S.
-        nnoremap S :%s//g<Left><Left>
+          set listchars=tab:→\ ,space:·,nbsp:␣,trail:•,eol:¶,precedes:«,extends:»
+          set clipboard+=unnamedplus
 
-        " save file with ,w
-        map <leader>w :w<cr><Space>
+          " Replace-all is aliased to S.
+          nnoremap S :%s//g<Left><Left>
 
-        " spellcheck
-        set spell spelllang=en_us
-        setlocal spell! spelllang=en_us
-      '';
-      # vimPlugins inspired from Alexnortung
-      # https://discourse.nixos.org/t/neovim-no-longer-uses-config-or-plugins/13399/4
-      packages.nix = with pkgs.vimPlugins; {
-        start = [
-          vim-surround  # shortcuts for setting () {} etc.
-          vim-gitgutter # git diff in sign column
-          # vim-airline   # nice and light status bar # doesn't work nicely with tmux
-          # coc-nvim coc-git coc-highlight coc-python coc-rls coc-vetur coc-vimtex coc-yaml coc-html coc-json # auto completion
-          vim-nix       # nix highlight
-          vimtex        # latex stuff
-          fzf-vim       # fuzzy finder through vim
-          nerdtree      # file structure inside nvim
-          rainbow       # color parenthesis
-          # gruvbox-nvim  # theme
-          catppuccin-nvim # theme
-          goyo-vim      # write prose
-          limelight-vim # prose paragraph highlighter
-        ];
-        opt = [];
+          " save file with ,w
+          map <leader>w :w<cr><Space>
+
+          " spellcheck
+          set spell spelllang=en_us
+          setlocal spell! spelllang=en_us
+        '';
+
+        # vimPlugins inspired from Alexnortung
+        # https://discourse.nixos.org/t/neovim-no-longer-uses-config-or-plugins/13399/4
+        packages.nix = with pkgs.vimPlugins; {
+          start = [
+            vim-surround    # shortcuts for setting () {} etc.
+            vim-gitgutter   # git diff in sign column
+            # vim-airline   # nice and light status bar (disabled for tmux)
+            # coc-nvim coc-* plugins (disabled for now)
+            vim-nix         # nix highlight
+            vimtex          # latex stuff
+            fzf-vim         # fuzzy finder through vim
+            nerdtree        # file structure inside nvim
+            rainbow         # color parenthesis
+            # gruvbox-nvim  # theme
+            catppuccin-nvim # theme
+            goyo-vim        # write prose
+            limelight-vim   # prose paragraph highlighter
+          ];
+          opt = [];
+        };
       };
     };
   };
 }
-