fix: formatting (luafmt), naming conventions and assertion

lua/catppuccino/core/integrations/nvimtree.lua

@@ -2,14 +2,11 @@ local M = {}
 
 function M.get(cpt)
     local config = require("catppuccino.config").options
-    local rootFolderColor = cpt.black
-    if
-      config.integrations
-      and config.integrations.nvimtree
-      and type(config.integrations.nvimtree) == "table"
-      and config.integrations.nvimtree.show_root
-    then
-      rootFolderColor = cpt.blue
+
+    local root_dir_color = cpt.bg_sidebar
+
+    if (config.integrations.nvimtree.show_root) then
+        root_dir_color = cpt.blue
     end
 
     return {
@@ -20,7 +17,7 @@ function M.get(cpt)
         NvimTreeEmptyFolderName = {fg = cpt.blue_br},
         NvimTreeIndentMarker = {fg = cpt.comment},
         NvimTreeVertSplit = {fg = cpt.black, bg = cpt.black},
-        NvimTreeRootFolder = {fg = rootFolderColor, style = "bold"},
+        NvimTreeRootFolder = {fg = root_dir_color, style = "bold"},
         NvimTreeSymlink = {fg = cpt.magenta},
         NvimTreeStatuslineNc = {fg = cpt.black, bg = cpt.black},
         NvimTreeGitDirty = {fg = cpt.git.change},