Merge pull request #5175 from weseek/fix/pageservice-can-delete-completely

fix: Internal server error occured when "Restrict complete deletion of pages" option's value is "Admin and author"

packages/app/src/server/service/page.js

@@ -109,7 +109,8 @@ class PageService {
       return true;
     }
     if (pageCompleteDeletionAuthority === 'adminAndAuthor') {
-      return (operator._id.equals(creatorId));
+      const operatorId = operator?._id;
+      return (operatorId != null && operatorId.equals(creatorId));
     }
 
     return false;