Select2 - Getting select2.full.min.js?ver=1.0.0:2 Uncaught TypeError: Cannot read property 'length' of undefined error

Select2 - Getting select2.full.min.js?ver=1.0.0:2 Uncaught TypeError: Cannot read property 'length' of undefined error

I think I'm almost there! I am getting expected result from my php script for the following code; but for some reason, I'm getting following error:

  1. select2.full.min.js?ver=1.0.0:2 Uncaught TypeError: Cannot read property 'length' of undefined
  2.     at d (select2.full.min.js?ver=1.0.0:2)


----- 
$("#jobSkills").select2({
    ajax: {
        url: ajax_object.ajax_url + "?action=autoSkills",
        dataType: 'json',
        delay: 250,
        type: 'POST',
        data: function (params) {
            return {
                skill: params.term,
                page: params.page
            };
        },
        processResults: function (data, params) {

            params.page = params.page || 1;
            console.log(data);

            return {
                results: data.items,
                pagination: {
                    more: (params.page * 30) < data.total_count
                }
            };
        },
        cache: true
    },
    minimumInputLength: 1,
    tags: "true",
    tokenSeparators: [',', '#'],
    maximumSelectionLength: 3,
    placeholder: "Ex. Java, MS Office, SEO"
    //data:
});

I figured out that the problem is most likely with results: data.items line.