Cannot remove last bookmark when multiple items exist and `separate_save_and_remove` is true

[blast-yuki]

Steps to reproduce:

1. Run the following code as nvim --clean -u minimal.lua:

   minimal.lua

   vim.env.LAZY_STDPATH = '.repro'
   load(vim.fn.system('curl -s https://raw.githubusercontent.com/folke/lazy.nvim/main/bootstrap.lua'))()
   
   vim.g.mapleader = vim.keycode('<Space>')
   vim.g.maplocalleader = vim.keycode('<Bslash>')
   
   local plugins = {
     {
       'otavioschwanck/arrow.nvim',
       dependencies = { 'nvim-tree/nvim-web-devicons' },
       opts = {
         leader_key = '<localleader>',
         separate_save_and_remove = true,
         show_icons = true,
         mappings = {
           edit = 'e',
           delete_mode = 'd',
           clear_all_items = 'C',
           toggle = 'a', -- used as save if separate_save_and_remove is true
           open_vertical = 'v',
           open_horizontal = 's',
           quit = 'q',
           remove = 'x', -- only used if separate_save_and_remove is true
           next_item = ']',
           prev_item = '[',
         },
         window = { border = 'rounded' },
       },
     },
   }
   
   require('lazy.minit').repro({ spec = plugins })

2. Add two or more items to the list using a.

3. Try to remove all bookmarks using x.

Expected Behavior:

The last bookmark should be removable, regardless of how many items are in the list. Currently, it only works correctly when there is a single item.