I had some issues getting started with this module as the input could not be found when the element is connected.

Debugging I found it was due to

It was then I realised that the javascript needs to be run after the element is on the page. I was able to verify this by changing the example provided such that the javascript tag was in the head of the page.

Should there be a console log or should this case be handled?

I suspect that this might mean this element cannot be added to the page dynamically if the javascript is already present.