When installing a new app with this module installed, the Odoo returns a singleton error. It comes from the write function on the res_user python script. I modified the function to the code below.

def write(self, vals):
    """
    Else the menu will be still hidden even after removing from the list
    """
    res = super(HideMenuUser, self).write(vals)
    for record in self:
        for menu in record.hide_menu_ids:
            menu.write({
                'restrict_user_ids': [(4, record.id)]
            })
    self.clear_caches()
    return res

There seems to be an issue with this module, at least for Odoo 14, in terms of this addon's interaction with the Operating Units modules.   If you try to add users to a Sales Team within a specific operating Unit, and you are also trying to restrict those users' lists of available menu, you will get an error.    " ValueError: Expected singleton: res.users .... "   If you're not using operating units, there seems to be no problem.  If you do not restrict menu items you can add users (in specific operating unit) to the sales team without issues.