SlRadioGroup / SlRadio has weird click behavior when using validation and empty values

[schilchSICKAG]

Describe the bug

When using an <sl-radio-group> with required set to true, it is not possible to select <sl-radio> elements that do not have a value property set when clicking on the item the first time.

To Reproduce

Steps to reproduce the behavior:

1. Open the codepen https://codepen.io/schilchSICKAG/pen/JjgOxyv?editors=1000. It extends the shoelace documentation for <sl-ragio-group> with a custom <sl-radio> that has no value set.
2. Select a valid option (all options except the second one) and submit. Everything should be fine.
3. Try to click the second radio. You will see it does nothing.
4. Try to click the second radio again. It will now select the value and will be invalid.

Browser / OS

• OS: [e.g. Mac, Windows] All
• Browser: [e.g. Chrome, Firefox, Safari] All
• Browser version: [e.g. 22] All

Additional information

We ran into this while writing a generic custom validation wrapper component (what a word!) for our shoelace based design system (which by the way, may also be of interest for you?) and initially thought this would be an implementation problem on our side.

Although I have not looked into this issue for now, would be happy to provide a PR for this if requested.