ui: avoid wrong transform

packages/ui-default/pages/problem_detail.page.jsx

@@ -193,6 +193,10 @@ const page = new NamedPage(['problem_detail', 'contest_detail_problem', 'homewor
             </div>
           `));
         } else {
+          if ($(e).next()[0].tagName !== 'UL') {
+            cnt--;
+            return;
+          }
           $(e).html($(e).html().replace(info, ''));
           $(e).next('ul').children().each((j, ele) => {
             $(ele).after(`