core&ui: language selection bug fix

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

@@ -3,6 +3,7 @@ import $ from 'jquery';
 import yaml from 'js-yaml';
 import React from 'react';
 import { createRoot } from 'react-dom/client';
+import Notification from 'vj/components/notification';
 import { downloadProblemSet } from 'vj/components/zipDownloader';
 import { NamedPage } from 'vj/misc/Page';
 import delay from 'vj/utils/delay';

packages/ui-default/pages/problem_submit.page.tsx

@@ -5,6 +5,10 @@ import getAvailableLangs from 'vj/utils/availableLangs';
 
 const page = new NamedPage(['problem_submit', 'contest_detail_problem_submit', 'homework_detail_problem_submit'], async () => {
   const { config } = UiContext.pdoc;
+  if (config.type === 'submit_answer') {
+    $('[name="lang"]').val('_');
+    return;
+  }
   const availableLangs = getAvailableLangs(config.langs);
   const mainLangs = {};
   const preferences = [($('[name="lang"]').val() as string) || ''];