#3267588: Check if the original severity exists before comparing it, to avoid the notice

Closes #3267588

trusted_reverse_proxy.module

@@ -21,7 +21,7 @@ function trusted_reverse_proxy_preprocess_status_report_page(&$variables) {
 
   $container = \Drupal::getContainer();
   $severity = $container->getParameter('trusted_reverse_proxy');
-  $originalSeverity = $variables['requirements']['#requirements']['trusted_host_patterns']['severity'];
+  $originalSeverity = $variables['requirements']['#requirements']['trusted_host_patterns']['severity'] ?? NULL;
   if ($originalSeverity !== $severity['severity']) {
     $variables['requirements']['#requirements']['trusted_host_patterns']['severity'] = $severity['severity'];
     // Mock an element for rendering to retrieve the counters.