"An invalid form control is not focusable" on multi-step forms with mandatory conditional checkbox groups #128

When a powermail multi-step form contains a mandatory checkbox group (multiple checkboxes sharing name="…[]") that is conditionally hidden/shown by EXT:powermail_cond, submitting the form after checking a non-first checkbox of that group produces a browser console error:

An invalid form control with name='tx_powermail_pi1[field][<marker>][]' is not focusable.

and blocks form submission.

Root cause:

Two bugs in PowermailConditions.js:

1. #getFieldByMarker returns only the first checkbox. It uses querySelector (singular), so #hideField/#showField only disable/enable and derequire/rerequire the first checkbox of a multi-value group. The remaining checkboxes keep their validation state unchanged.
2. #rerequireField converts data-powermail-required to native required. Powermail renders multi-checkbox mandatory fields with data-powermail-required="true" (not native required) and handles "at least one checked" via data-powermail-multiple. The old #rerequireField unconditionally restored a native required attribute, which the browser's reportValidity() (called by #submitListener) then tried to enforce. In a multi-step form the field's fieldset is display:none (hidden by the morestep navigation), so the browser cannot focus the invalid checkbox and emits the "not focusable" error.

Trigger conditions (all required):

• Multi-step form (moresteps=1) with 2+ pages
• Mandatory checkbox group on a non-final step, conditionally hidden by powermail_cond
• Powermail JS validation active (data-powermail-validate)
• User checks a non-first checkbox of the shown group, then navigates to the next step and submits

Fix:

• #hideField/#showField: iterate querySelectorAll('input, select, textarea') over the wrapping container so all inputs in a multi-value group are disabled/enabled and derequired/rerequired.
• #derequireField/#rerequireField: bookmark which attribute was present (required or data-powermail-required) and restore the same one, preserving powermail's custom validation mechanism for multi-checkbox groups.

TYPO3: 13
Powermail: 13.1.0
Powermail Cond: 13.1.2