PHP Fatal error: Cannot set directive after finalization

$_data->set('HTML.AllowedElements', $_elem);

function ujEditorTemplates_html_purifier_listener($_data, $_user, $_conf, $_args, $event)
{

	$_elem = $_data->get('HTML.AllowedElements');

	// Set additional Bootstrap elements
	$_elem['abbr'] = 1;
	$_elem['blockquote'] = 1;
	$_elem['cite'] = 1;
	// ...plus a load more of these...

	$_elem = implode(',', array_keys($_elem));
	$_data->set('HTML.AllowedElements', $_elem);

	$_attr = $_data->get('HTML.AllowedAttributes');

	// Set additional Bootstrap attributes
	$_attr['abbr.title'] = 1;
	$_attr['cite.title'] = 1;
	$_attr['blockquote.class'] = 1;
	// ...plus a load more of these...

	$_attr = implode(',', array_keys($_attr));
	$_data->set('HTML.AllowedAttributes', $_attr);

    return $_data;
}

$pc->autoFinalize = false;

function jrFramer_html_purifier_listener($_data,$_user,$_conf,$_args,$event)
{
    if (isset($_conf['jrFramer_active']) && $_conf['jrFramer_active'] == 'on') {
        $_data->set('HTML.SafeIframe', true);
        $_data->set('URI.SafeIframeRegexp', '%(.*)%');
        
        // ADDITIONAL TESTING CODE 

	$_elem = $_data->get('HTML.AllowedElements');

	// Set additional elements
	$_elem['abbr'] = 1;
	$_elem['blockquote'] = 1;
	$_elem['cite'] = 1;

	$_elem = implode(',', array_keys($_elem));
	$_data->set('HTML.AllowedElements', $_elem);

	$_attr = $_data->get('HTML.AllowedAttributes');

	// Set additional attributes
	$_attr['abbr.title'] = 1;
	$_attr['cite.title'] = 1;
	$_attr['blockquote.class'] = 1;
	
	// this needs to be present in the function in util.php as well
	$_attr['blockquote.data-content'] = 1;

	$_attr = implode(',', array_keys($_attr));
	$_data->set('HTML.AllowedAttributes', $_attr);

        
    }
    return $_data;
}

$pc->autoFinalize = false;

<blockquote class="blockquote-reverse" data-content="test-content-12">
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
  <footer>Someone famous in <cite title="Source Title">Source Title</cite></footer>
</blockquote>

$def->addAttribute('a', 'data-lightbox', 'Text');

$def->addAttribute('blockquote', 'data-content', 'Text');

span,strong,em,a,b,u,i,p,div,br,img,h1,h2,h3,h4,pre,
hr,ul,ol,li,table,tbody,th,tr,td,figure,figcaption,
figure.class,figcaption.class,iframe,blockquote,footer,
cite,cite.class,cite.title,blockquote.class,blockquote.data-content

data-content=

// ------- additional code -------                    
// comment out unset($_att); on line 1559 in order for this to work
foreach ($_att as $attr) {
    if (!strpos($attr, ',')) { // ignore jamrooms lists of element.attributes defined above
        list($element,$attribute) = explode('.', $attr);
        $def->addAttribute($element, $attribute, 'Text'); // add to HTML Definition
    }
}
unset($_att);
// ------- end additional code -------