refactor(#2731): resolve warnings

Author: alex-courtis

lua/nvim-tree/live-filter.lua

@@ -27,8 +27,8 @@ local function reset_filter(node_)
     :iterate()
 end
 
-local overlay_bufnr = nil
-local overlay_winnr = nil
+local overlay_bufnr = 0
+local overlay_winnr = 0
 
 local function remove_overlay()
   if view.View.float.enable and view.View.float.quit_on_focus_loss then
@@ -46,8 +46,8 @@ local function remove_overlay()
 
   vim.api.nvim_win_close(overlay_winnr, true)
   vim.api.nvim_buf_delete(overlay_bufnr, { force = true })
-  overlay_bufnr = nil
-  overlay_winnr = nil
+  overlay_bufnr = 0
+  overlay_winnr = 0
 
   if M.filter == "" then
     M.clear_filter()