I am using the sample code in my body:

<div id="mly" ref="mlyRef"></div>

And javascript code:

if (this.$refs.mlyRef instanceof HTMLElement) {
    var mly = new Viewer({
        accessToken:"",
        container: this.$refs.mlyRef,
        imageId: "",
        component: { cover: false }
    });
}

Any idea what might be generating the following error - Invalid type: 'container' must be a String or HTMLElement."