lualine: match theme with nvim colorscheme

modules/default.nix

@@ -1,4 +1,4 @@
-{ lib, pkgs, ... }:
+{ lib, config, pkgs, ... }:
 
 {
   imports = [
@@ -9,6 +9,11 @@
     ./telescope.nix
   ];
 
+  assertions = [{
+    assertion = !config.colorschemes.kanagawa.enable && config.plugins.lualine.settings.options.theme == "kanagawa";
+    message = "NixVim `colorschemes.kanagawa.enable` is disabled but `plugins.lualine.settings.options.theme` is set to `kanagawa`.";
+  }];
+
   extraPlugins = with pkgs.vimPlugins; [
     vim-fetch # accept ./path/to/file:123 as line numbers
   ];
@@ -81,16 +86,16 @@
       settings = {
         options = {
           globalstatus = true;
-          theme = "onedark";
+          theme = lib.mkDefault "kanagawa";
         };
         # https://github.com/nvim-lualine/lualine.nvim?tab=readme-ov-file#filename-component-options
         sections = {
-          lualine_b = [ {
+          lualine_b = [{
             sources = [ "nvim_diagnostic" "nvim_lsp" ];
-          } ];
-          lualine_c = [ {
+          }];
+          lualine_c = [{
             path = 1;
-          } ];
+          }];
         };
       };
     };