Issue #2956643 by Rade, Dave Reid: Fixed xmlsitemap_requirements()...

Issue #2956643 by Rade, Dave Reid: Fixed xmlsitemap_requirements() LogicException: Render context is empty, because render() was called outside of a renderRoot() or renderPlain() call.

xmlsitemap.install

@@ -25,14 +25,15 @@ function xmlsitemap_requirements($phase) {
   $missing_extensions = array_diff($required_extensions, array_filter($required_extensions, 'extension_loaded'));
 
   if (!empty($missing_extensions)) {
-    $items = ['#type' => 'item_list', 'items' => $missing_extensions];
+    $items = ['#theme' => 'item_list', '#items' => $missing_extensions];
     $requirements['xmlsitemap_php_extensions'] = [
       'title' => $t('XML sitemap PHP extensions'),
       'value' => $t('Disabled'),
       'severity' => REQUIREMENT_ERROR,
-      'description' => $t("The XML sitemap module requires you to enable the PHP extensions in the following list (see the <a href=\"@xmlsitemap_requirements\">module's system requirements page</a> for more information):", [
+      'description' => $t("The XML sitemap module requires you to enable the PHP extensions in the following list (see the <a href=\"@xmlsitemap_requirements\">module's system requirements page</a> for more information): @extensions", [
         '@xmlsitemap_requirements' => 'https://www.drupal.org/documentation/modules/xmlsitemap/requirements',
-      ]) . \Drupal::service('renderer')->render($items),
+        '@extensions' => \Drupal::service('renderer')->renderPlain($items),
+      ]),
     ];
   }
 
@@ -69,7 +70,7 @@ function xmlsitemap_requirements($phase) {
         $items = ['#theme' => 'item_list', '#items' => array_keys($directories)];
         $requirements['xmlsitemap_directory']['value'] = $t('Not found or not writable');
         $requirements['xmlsitemap_directory']['severity'] = REQUIREMENT_ERROR;
-        $requirements['xmlsitemap_directory']['description'] = $t('The following directories were not found or are not writable by the server. See <a href="@docpage">@docpage</a> for more information. @directories', ['@directories' => \Drupal::service('renderer')->render($items), '@docpage' => 'https://www.drupal.org/node/244924']);
+        $requirements['xmlsitemap_directory']['description'] = $t('The following directories were not found or are not writable by the server. See <a href="@docpage">@docpage</a> for more information. @directories', ['@directories' => \Drupal::service('renderer')->renderPlain($items), '@docpage' => 'https://www.drupal.org/node/244924']);
       }
     }
     $sitemaps = xmlsitemap_sitemap_load_multiple();