Disable problem creation when not logged in

modules/problem.js

@@ -84,6 +84,7 @@ app.get('/problem/:id/edit', async (req, res) => {
     let problem = await Problem.fromID(id);
 
     if (!problem) {
+      if (!res.locals.user) throw 'Permission denied.';
       problem = await Problem.create();
       problem.id = id;
       problem.allowedEdit = true;

views/problems.ejs

@@ -1,6 +1,7 @@
 <% this.title = '题库' %>
 <% include header %>
 <div class="padding">
+  <% if (user) { %>
     <div class="ui grid">
       <div class="row">
         <div class="column">
@@ -8,6 +9,7 @@
         </div>
       </div>
     </div>
+  <% } %>
   <table class="ui very basic center aligned table">
     <thead>
       <tr>