Pull Request for Issue #43800.

Summary of Changes

Updated subform JavaScript behaviours to look for .switcher when .radio is not found.

Testing Instructions

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.

Actual result BEFORE applying this Pull Request

A 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.)

Expected result AFTER applying this Pull Request

A subform item is created and added to the subform without any JavaScript errors occurring.

Link to documentations

No documentation changes for docs.joomla.org needed.
No documentation changes for manual.joomla.org needed.