It's not working too with a simples YESNO and togglesOn in a text field:
$form->add( new \IPS\Helpers\Form\YesNo( 'field1', \IPS\Settings::i()->field1, FALSE, array( 'togglesOn' => array( 'field2' ) ) ) );
$form->add( new \IPS\Helpers\Form\Text( 'field12', \IPS\Settings::i()->field2, TRUE, array(), NULL, NULL, NULL, 'field2' ) );
I have to make a custom validation to avoid the error.