Improve #radios required validation and error placement.

Confirmed, #8 works. Make sure to enable `inline_form_errors` which I had forgot to do, causing it not to work initially.

I can confirm #8 works but sometimes the assumption of $complete_form['#type'] always existing can generate warning messages, for instance when you access `/admin/config/regional/language`when you have language module active.
I just added a check to mitigate this situation. Thanks!

Hi, thanks everyone for your contribution to this issue.
I tried to fix the issue using your approach for webforms (clientside_validation + webform_clientside_validation + inline_form_errors), but the issue was still happening.
In my case, my theme extends from stable9 that doesn't add classes like "form-checkboxes", "form-radios", or "form-type-[type]" to the form elements, which are used in the webform_clientside_validation js selectors.
Stable9 adds "js-form-type-[type]" and forgets about the "form-type-[type]" as in the snippet below:

{%
  set classes = [
    'js-form-item',
    'form-item',
+        'form-type-' ~ type|clean_class, (THIS IS MISSING)
    'js-form-type-' ~ type|clean_class,
    'form-item-' ~ name|clean_class,
    'js-form-item-' ~ name|clean_class,
    title_display not in ['after', 'before'] ? 'form-no-label',
    disabled == 'disabled' ? 'form-disabled',
    errors ? 'form-item--error',
  ]
%}

I fixed the placement issue by overriding the form-element.html.twig and adding the code above. For the fieldset.html.twig, I added the following:

{%
  set classes = [
  'js-form-item',
  'form-item',
  'js-form-wrapper',
  'form-wrapper',
+  'form-' ~ element['#type'] (THIS IS MISSING)
]

I reported this core bug https://www.drupal.org/project/drupal/issues/3380021 🐛 Stable9 form-element template misses form-type-* class Fixed , so it might avoid issues with themes based on stable9.

Solution/patch #12 works for me. Both radios and checkboxes (as webforms elements) display error messages beneath all options.

Thanks everyone, I would really appreciate if we can have some tests added to the patch.

I am trying to reproduce and confirm the fix and improve the solution (make it generic and work even without inline_form_errors module), I have got radios working but not able to make normal required validation work for checkboxes.