Merge pull request #6571 from WoltLab/62-empty-page-title-fix

Fix exception when editing system pages without a title

Author: BurntimeX

wcfsetup/install/files/lib/acp/form/PageEditForm.class.php

@@ -375,4 +375,15 @@ public function assignVariables()
             'supportsCustomUrl' => $this->supportsCustomUrl,
         ]);
     }
+
+    #[\Override]
+    protected function validateTitle()
+    {
+        if ($this->page->pageType === 'system' && $this->page->requireObjectID) {
+            // Allow an empty title for pages that dynamically generate their title based on a given ID (e.g. `ArticlePage`).
+            return;
+        }
+
+        parent::validateTitle();
+    }
 }