Steps to reproduce the issue

1. Add the following subform to a form:

<field
    name="switcher_test_subform"
    type="subform"
    label="Switcher Test"
    multiple="true"
    layout="joomla.form.field.subform.repeatable">
    <form>
        <fieldset>
            <field
                name="switcher_test"
                type="radio"
                label="Switcher Test"
                layout="joomla.form.field.radio.switcher"
                default="0"
                >
                <option value="0">JNO</option>
                <option value="1">JYES</option>
            </field>
        </fieldset>
    </form>
</field>

2. Access the form and click + to add a subform item.

Expected result

The subform item is created and added to the subform.

Actual result

The subform item is created and added to the subform, but the following JavaScript error occurs, which interferes with any other JavaScript attempting to run.

TypeError: Cannot read properties of null (reading 'nodeName')
    at joomla-field-subform.js?25ff4b:305:31
    at Array.forEach (<anonymous>)
    at JoomlaFieldSubform.fixUniqueAttributes (joomla-field-subform.js?25ff4b:263:14)
    at JoomlaFieldSubform.addRow (joomla-field-subform.js?25ff4b:195:10)
    at JoomlaFieldSubform.<anonymous> (joomla-field-subform.js?25ff4b:95:16)

(Error trace taken with debug mode enabled.)

System information (as much as possible)

Joomla 5.1.2
PHP 8.3.8