fix domain handling

Author: deer-wmde

app/Http/Controllers/WikiController.php

@@ -42,6 +42,9 @@ public function create(Request $request): Response {
         $user = $request->user();
 
         $submittedDomain = strtolower((string) $request->input('domain'));
+        if (empty($submittedDomain)) {
+            abort(422, 'Missing domain');
+        }
         $submittedDomain = DomainHelper::encode($submittedDomain);
 
         $domainValidator = $this->domainValidator->getValidator($submittedDomain);