fix(pack): explicitly close confirmation window #37861

Problem: Executing `nvim_buf_delete()` does not guarantee that the
  window which shows the buffer is going to close after `:write` or
  `:quit`. In particular, if there is no listed buffer present.

Solution: Explicitly close the window that was created for confirmation
  buffer. Use `pcall` to catch cases when the window was already closed
  or when it is the last window.

runtime/lua/vim/pack.lua

@@ -1122,6 +1122,7 @@ local function show_confirm_buf(lines, on_finish)
   local win_id = api.nvim_get_current_win()
 
   local delete_buffer = vim.schedule_wrap(function()
+    pcall(api.nvim_win_close, win_id, true)
     pcall(api.nvim_buf_delete, bufnr, { force = true })
     vim.cmd.redraw()
   end)