ISTWCMS-5409: Adding support for empty key.

src/Commands/UwDrushCommands.php

@@ -219,8 +219,14 @@ class UwDrushCommands extends DrushCommands {
    *   - Return light weight cron url with key.
    */
   public function getLightWeightCronUrl(): string {
+    $url = '';
     $host = $this->request->getSchemeAndHttpHost();
-    return $host . '/scheduler/cron/' . $this->getLightWeightCronKey();
+
+    if ($key = $this->getLightWeightCronKey()) {
+      $url = $host . '/scheduler/cron/' . $key;
+    }
+
+    return $url;
   }
 
 }