修复一些小错误

ui/pages/problem_detail.page.js

@@ -168,9 +168,6 @@ const page = new NamedPage(['problem_detail', 'contest_detail_problem', 'homewor
     } = await loadReactRedux(ScratchpadReducer);
 
     const sock = new SockJs(Context.socketUrl);
-    sock.onopen = () => {
-      sock.send(document.cookie);
-    };
     sock.onmessage = (message) => {
       const msg = JSON.parse(message.data);
       store.dispatch({