PHP Warning: A non-numeric value encountered in categories_ul_generator.php

This error started in tpl_modules_mobile_menu.php

As the result of a number of categories having the special character '&' instead of '&' like Salt & Vinegar should be Salt & Vinegar

Changing line 38:
$menulist = $zen_CategoriesUL->buildTree(true);

to this:
$menulist = $zen_CategoriesUL->buildTree();

Allows the mobile menu to operate correctly again.

Note there are updates related to this function here:

and perhaps here as well: