Prevent CMS pages with blank titles

ref https://www.woltlab.com/community/thread/294440-titel-einer-seite-wird-ausblendbar-zum-pflichtfeld/

Author: BurntimeX

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

@@ -537,18 +537,16 @@ protected function normalizeCustomUrl(string $customUrl): string
      */
     protected function validateTitle()
     {
-        if ($this->addPageToMainMenu) {
-            if ($this->isMultilingual) {
-                foreach ($this->availableLanguages as $language) {
-                    if (empty($this->title[$language->languageID])) {
-                        throw new UserInputException('title_' . $language->languageID);
-                    }
-                }
-            } else {
-                if (empty($this->title[0])) {
-                    throw new UserInputException('title');
+        if ($this->isMultilingual) {
+            foreach ($this->availableLanguages as $language) {
+                if (empty($this->title[$language->languageID])) {
+                    throw new UserInputException('title_' . $language->languageID);
                 }
             }
+        } else {
+            if (empty($this->title[0])) {
+                throw new UserInputException('title');
+            }
         }
     }