chore(luacheck): fix luacheck issues

.luacheckrc

@@ -8,6 +8,6 @@ ignore = {
 }
 
 -- Global objects defined by the C code
-read_globals = {
+globals = {
   "vim",
 }

lua/nvim-tree/lib.lua

@@ -462,7 +462,8 @@ function M.sibling(node, direction)
   local iter = get_line_from_node(node, true)
   local node_path = node.absolute_path
 
-  local line, parent = 0, nil
+  local line = 0
+  local parent, _
 
   -- Check if current node is already at root entries
   for index, entry in ipairs(M.Tree.entries) do

lua/nvim-tree/renderer.lua

@@ -26,7 +26,7 @@ local icon_padding = vim.g.nvim_tree_icon_padding or " "
 
 if icon_state.show_folder_icon then
   get_folder_icon = function(open, is_symlink, has_children)
-    local n = ""
+    local n
     if is_symlink and open then
       n = icon_state.icons.folder_icons.symlink_open
     elseif is_symlink then