Issue #3033766 by npralhad, a.dreichan, jacklee0410, hatuhay: Notice: Array to...

Issue #3033766 by npralhad, a.dreichan, jacklee0410, hatuhay: Notice: Array to string conversion in Drupal\Core\Template\AttributeArray->__toString()

templates/navigation/menu.html.twig

@@ -48,7 +48,7 @@
           set link_classes = [
             'nav-link',
             item.in_active_trail ? 'active',
-            item.url.getOption('attributes').class ? item.url.getOption('attributes').class,
+            item.url.getOption('attributes').class ? item.url.getOption('attributes').class | join(''),
           ]
         %}
         {{ link(item.title, item.url, {'class': link_classes}) }}