undefined
TypeError: Cannot read properties of undefined (reading 'username')
    at /Users/ochaemin/workspace/cwnu-db-make-community/web/app.js:34:23
    at Layer.handle [as handle_request] (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/layer.js:95:5)
    at next (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/route.js:144:13)
    at Route.dispatch (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/route.js:114:3)
    at Layer.handle [as handle_request] (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/layer.js:95:5)
    at /Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/index.js:284:15
    at Function.process_params (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/index.js:346:12)
    at next (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/index.js:280:10)
    at expressInit (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/middleware/init.js:40:5)
    at Layer.handle [as handle_request] (/Users/ochaemin/workspace/cwnu-db-make-community/web/node_modules/express/lib/router/layer.js:95:5)

      <div class="post-list">
       <!-- 게시글 목록 -->
         <table id="board">
           <thead>
             <tr>
               <th style="width: 10%; height: 6vh;">게시글 번호</th>
               <th style="width: 40%; height: 6vh;">제목</th>
               <th style="width: 20%; height: 6vh;">작성 일자</th>
               <th style="width: 10%; height: 6vh;">작성자</th>
             </tr>
           <thead>
           <!-- 게시글 목록 보여주는 ejs -->
           <tbody>
             <% for (i=0; i<list.length; i++) { %>
             <tr>
               <td><%=list[i].게시글ID%></td>
               <td style="text-align:left"><%=list[i].제목%></td>
               <td><%=list[i].작성일자%></td>
               <td><%=list[i].작성자%></td>
             </tr>
             <% } %>
           <tbody>
        </table>
       </div>

app.get('/products/:page', (req, res) => {
     const page_size = 3; // 각 페이지의 최대 항목 수
     const page = req.params.page || 1 // if page is null then 1, 현재 페이지 번호
     console.log(page);

     const sql = 'SELECT * FROM 게시글';
     maria.query(sql, (err, rows, fields) => {
         for(let i=0; i<rows.length; i++){
             console.log('rows'+JSON.stringify(rows[i]));
             rows[i].작성일자 = moment(rows[i].작성일자).format('YYYY-MM-DD');
         }
         console.log("rows: "+rows[1].date);
         if (err) cosole.log('QUERY FAIL\n' + err);
         else res.render('mainpage.ejs', {list:rows});
     });
 });