ui: fix createHint

packages/ui-default/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.25.7",
+  "version": "4.25.8",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "hydro.js",

packages/ui-default/pages/problem_files.page.js

@@ -254,9 +254,9 @@ const page = new NamedPage('problem_files', () => {
   $(document).on('click', '[name="download_selected_testdata"]', () => handleClickDownloadSelected('testdata'));
   $(document).on('click', '[name="download_selected_file"]', () => handleClickDownloadSelected('additional_file'));
   $(document).on('vjContentNew', (e) => {
-    createHint('Hint::icon::testdata', $(e.target).find('[name="create_testdata"]').get(0).parentNode.parentNode.children[0]);
+    createHint('Hint::icon::testdata', $(e.target).find('[name="create_testdata"]').get(0)?.parentNode?.parentNode?.children?.[0]);
   });
-  createHint('Hint::icon::testdata', $(document).find('[name="create_testdata"]').get(0).parentNode.parentNode.children[0]);
+  createHint('Hint::icon::testdata', $(document).find('[name="create_testdata"]').get(0)?.parentNode?.parentNode?.children?.[0]);
 });
 
 export default page;