[FIX] Add MenuItemPage title and subtitle type casting to string

Classes/Domain/Model/MenuItemPage.php

@@ -13,9 +13,9 @@ class MenuItemPage extends MenuItem
      */
     public function getTitle(): string
     {
-        return (string) $this->title ?:
+        return (string) ($this->title ?:
             ObjectAccess::getPropertyPath($this, 'page.navTitle') ?:
-                ObjectAccess::getPropertyPath($this, 'page.title');
+                ObjectAccess::getPropertyPath($this, 'page.title'));
     }
 
     /**
@@ -23,7 +23,7 @@ class MenuItemPage extends MenuItem
      */
     public function getSubtitle(): string
     {
-        return (string) $this->subtitle ?:
-            ObjectAccess::getPropertyPath($this, 'page.subtitle');
+        return (string) ($this->subtitle ?:
+            ObjectAccess::getPropertyPath($this, 'page.subtitle'));
     }
 }