Issue #3495238: Do not fail on missing IP address

src/EventSubscriber/CrowdSec.php

@@ -74,7 +74,11 @@ class CrowdSec extends HttpExceptionSubscriberBase {
    *   The event to process.
    */
   public function on4xx(ExceptionEvent $event): void {
-    $this->buffer->addWhisperSignal($event->getRequest()->getClientIp());
+    $ip = $event->getRequest()->getClientIp();
+    if (empty($ip)) {
+      return;
+    }
+    $this->buffer->addWhisperSignal($ip);
   }
 
   /**