Cannot create select if it does not have ID

[TivoSoho]

We usually do not add IDs - it has no importance to us. However it fails to create a select this way. The line that fails:
customDropdown.classList.add(originalSelect.id),

I cannot even fathom how to make a PR as I do not how much you actually use it. I am not even sure why one would add an ID to a class list...

[powderflask]

This is also causing an issue for us in a tabbed layout where there is filter form on each tab. The filter forms are generated by generic code, so their select widgets don't have unique id's.
I'm not much of a JS programmer, but I wonder if it might be possible to store a reference to the select DOM element rather than relying on its id? I'd be happy to work on this, but would like to know if this is even something that the maintainers would consider or think might be a fruitful direction?

Excellent job with this component btw - so good to have such a great option with zero dependencies.