Help with getting option "pageLoading" working

[a95tbirdsc]

Could someone help me figure out how to get jsGrid to load my data. I'm using the "pageLoading" option but it would appear the controller is not wanting to recognize my data. What am I missing?

Data

[{"ROW_NUMBER":1,"data":"[{\"data\":[{\"STUDENTPIDM\":1,\"STUDENTID\":111,\"STUDENTNAME\":\"Presley, Elvis\",\"AIDYEAR\":\"2425\",\"CATEGORY\":\"Deceased\",\"CATEGORIES\":null,\"COMMENTS\":\"Wish he was still here\"},{\"STUDENTPIDM\":2,\"STUDENTID\":222,\"STUDENTNAME\":\"Monroe, Marilyn\",\"AIDYEAR\":\"2324\",\"CATEGORY\":\"Deceased\",\"CATEGORIES\":null,\"COMMENTS\":\"Really miss her.\"},{\"STUDENTPIDM\":3,\"STUDENTID\":333,\"STUDENTNAME\":\"Dean, James\",\"AIDYEAR\":\"2425\",\"CATEGORY\":\"Deceased\",\"CATEGORIES\":null,\"COMMENTS\":\"Cool Actor\"}],\"itemcount\":\"3\"}]"}]

Controller Code:

        controller: {
          loadData: function (filter) {
                      return fetch("/internal/VD.XXXX")
                               .then(response => response.json()) 
                               .catch((error) => {
                                  toastr["error"]("Something went wrong.", "Error");
                               });

Error:

Uncaught (in promise) TypeError: this.data is undefined