Notice: Undefined variable: data in theme_item_list()

Backtrace of the notice. Looks like it gets thrown if there are no endpoints.

Array
(
    [0] => Array
        (
            [function] => theme_item_list
            [args] => Array
                (
                    [0] => Array
                        (
                            [items] => Array
                                (
                                )

                        )

                )

        )

    [1] => Array
        (
            [file] => includes/theme.inc
            [line] => 668
            [function] => call_user_func_array
        )

    [2] => Array
        (
            [file] => sites/all/modules/services/services.install
            [line] => 109
            [function] => theme
        )

    [3] => Array
        (
            [function] => services_requirements
        )

services_requirements. Looks like there is a print_r in here as well.