selected item in attached callback sets to 'undefined' when carousel-slides are included using dom-repeat template

[spachore]

I am using this component for showing dynamic content using dom-repeat template. It might happen that the imageList is blank for a short duration initially.

      <simple-carousel auto infinite-loop>
        <template is="dom-repeat" items="{{imageList}}" as="imageItem">
          <carousel-slide>
                 <img src="{{imageItem.imageURL}}">
          </carousel-slide>
        </template>
      </simple-carousel>

As the imageList is empty, the component does not get any slide to set as 'selected' item during attached callback. And the carousel fails to show any items even after the imageList gets filled with items, as the next() function does not have valid selected item.

This case of 'no-slides-initially' should be handled. The next() function should set the selected item, if it is 'undefined'.