address.ts:72 Uncaught (in promise) TypeError: Cannot set property 'stateShortName' of undefined

@bindable({ defaultBindingMode: bindingMode.twoWay }) address = new AddressDetails;

getStateData() {
    const headers = this.authService.header();

    let stateDropdown = fetch("/api/selectData/GetStatesAndCompanyStateId", {
        method: "GET",
        headers
    })
        .then(response => response.json())
        .then(data => {
            for (const key in data.stateDropDownList) {
                this.states[key] = data.stateDropDownList[key].stateShortName;
            }
            console.log("ADDRESS get state data: ", this.address);
            console.log("data: ", data)
            this.companyStateShortName = data.companyStateShortName;
            console.log("StateShortName: ", this.companyStateShortName)
        })
        .then(() => {
                console.log("this.address.addressLocation: ", typeof this.address, this.address)
            this.address.addressLocation.stateShortName = this.companyStateShortName;
            //}
        });

ADDRESS get state data: AddressDetails {__observers__: { … } } address1: undefinedaddress2: undefinedaddressLocation: undefined__observers__: { address1: SetterObserver, address2: SetterObserver, addressLocation: SetterObserver } get address1: ƒ()set address1: ƒ()get address2: ƒ()set address2: ƒ()get addressLocation: ƒ()set addressLocation: ƒ()__proto__: Object
    address.ts:62 data: { companyStateShortName: "VIC", stateDropDownList: Array(8) } companyStateShortName: "VIC"stateDropDownList: (8) [{ … }, { … }, { … }, { … }, { … }, { … }, { … }, { … }]__proto__: Object
    address.ts:64 StateShortName: VIC
    address.ts:71 this.address.addressLocation:  object AddressDetails {__observers__: { … } }
    address.ts:72 Uncaught (in promise) TypeError: Cannot set property 'stateShortName' of undefined
    at address.ts:72
    at<anonymous>