feat: support themes other than defaults

Try to activate a theme if not presented in defaults. Accordingly,
add the option `ui.colors` to provide the missing `hl_theme*` in
the custom theme.

lua/colors/init.lua

@@ -13,22 +13,34 @@ M.init = function(theme)
 
    if present then
       -- first load the base16 theme
-      base16(base16.themes(theme), true)
-
-      -- unload to force reload
-      package.loaded["colors.highlights" or false] = nil
-      -- then load the highlights
-      require "colors.highlights"
+      local ok, array = pcall(base16.themes, theme)
+
+      if ok then
+         base16(array, true)
+         -- unload to force reload
+         package.loaded["colors.highlights" or false] = nil
+         -- then load the highlights
+         require "colors.highlights"
+      else
+         pcall(vim.cmd, "colo " .. theme)
+      end
+   else
+      pcall(vim.cmd, "colo " .. theme)
    end
 end
 
 -- returns a table of colors for given or current theme
 M.get = function(theme)
-   if not theme then
-      theme = vim.g.nvchad_theme
+   local colors = require("core.utils").load_config().ui.colors
+
+   if #colors ~= 0 then
+      return require(colors)
+   else
+      if not theme then
+         theme = vim.g.nvchad_theme
+      end
+      return require("hl_themes." .. theme)
    end
-
-   return require("hl_themes." .. theme)
 end
 
 return M

lua/core/default_config.lua

@@ -46,6 +46,7 @@ M.options = {
 
 M.ui = {
    hl_override = "", -- path of your file that contains highlights
+   colors = "", -- path of your file that contains colors
    italic_comments = false,
    theme = "onedark", -- default theme