Undefined offset error in admin main menu

I'm building a site on a local xampp install with Perch Runway and added a new user.

I set a new role up for them and logged in as them (to see what is shown and what is not as... the things you can pick to allow or not seem limited compared to the actual number of things included in perch runway!) and i get the following error:

Notice: Undefined offset: 0 in C:\xampp\htdocs\salonsaver\admin\core\inc\main_start.php on line 46

It is appearing after Pages in the main menu (on all pages of the admin).

Only Pages and Users are showing in the menu (even though i did allow that user access to Assets). I don't know if that item is supposed to be hidden for non Admins or what (first time working with Perch Runway!)

Perch Runway: 2.8.6, PHP: 5.5.15, MySQL: mysqlnd 5.0.11-dev - 20120503 - $Id: bf9ad53b11c9a57efdb1057292d73b928b8c5c77 $, with PDO
Server OS: WINNT, apache2handler
Installed apps: content (2.8.6), assets (2.8.6), categories (2.8.6)
App runtimes: <?php $apps_list = array( 'content', 'categories', );
PERCH_LOGINPATH: /admin
PERCH_PATH: C:\xampp\htdocs\salonsaver\admin
PERCH_CORE: C:\xampp\htdocs\salonsaver\admin\core
PERCH_RESFILEPATH: C:\xampp\htdocs\salonsaver\admin\resources
Image manipulation: GD
PHP limits: Max upload 16M, Max POST 16M, Memory: 128M, Total max file upload: 16M
Resource folder writeable: Yes
HTTP_HOST: perch.local
DOCUMENT_ROOT: C:/xampp/htdocs/salonsaver
REQUEST_URI: /admin/core/settings/diagnostics/
SCRIPT_NAME: /admin/core/settings/diagnostics/index.php