Api Calls Queue with Vuejs 2

app.js

const app = new Vue({
    el: '#tool-app',
    data() {
        return {
            tivs: [],
            nextKey: 0
        }
    },
    mounted() {
        API.getAllTIV().then(response => {
            return response.json();
        }).then(json => {
            this.tivs = json.images
            this.getDecode();
        });
    },
    methods: {
        getDecode() {
            if (this.tivs.length > this.nextKey) {
                return API.getData(this.tivs[this.nextKey]).then(response => {
                    return response.json()
                }).then(json => {
                    this.nextKey++
                    console.log(json)
                }).catch(err => {
                    console.log(err)
                    this.nextKey++
                });
            } else {
                console.log('no existe el key ' + this.nextKey + ' en ese arreglo')
            }
        }
    },
    watch: {
        nextKey: function () {
            this.getDecode()
        }
    }
});