Steps to reproduce the issue

I'm experiencing a problem after update joomla! to version 3.8.6, the module menuwrench no load submenu items.
The option "Show Sub-menu Items" its ok.

In error.php

PHP Notice: Indirect modification of overloaded property Joomla\CMS\Menu\MenuItem::$children has no effect in /var/www/unm/modules/mod_menuwrench/helper.php on line 84,

In line 84 and context:

`
$this->app = joomla\CMS\factory::getApplication();
$this->db = joomla\CMS\factory::getDbo();

$this->menu = $this->app->getMenu();
$items = $this->menu->getItems(null, null);

foreach ($items as $key => $item)
{

		$items[$item->id] = $item;

		// If menu item is a category, add all articles as menu items
		if ($showCategoryItems && $this->isContent($item))
		{
			$items[$item->id]->hijo = $this->linkCategoryItems(
				$this->getCategoryItems($item->query['id']),
				$item->query['id'],
				$item->id
			);
		}

		unset($items[$key]);

		if ($item->parent_id != 1)
		{
			$items[$item->parent_id]->hijo[$item->id] = $item; <--Line 84
		}
	}

`

Expected result

Menu and submenu listed.

Actual result

Menu listed, the module can´t list submenus

System information (as much as possible)

Joomla! 3.8.6
OS: Debian
Php: 5.6

Additional comments