Fixed if no content

Signed-off-by: Toomore Chiang <[email protected]>

Author: toomore

templates/schedule_submissions.html

@@ -50,8 +50,8 @@ <h1 class="title">{{submissions[0].track.get('zh-tw', submissions[0].track['en']
                     <div class="content">
                         <h3>議程簡介</h3>
                         <div class="content box">
-                            {{ track_description.get('zh-tw')|safe }}
-                            {{ track_description.get('en')|safe }}
+                            {{ track_description.get('zh-tw', '')|safe }}
+                            {{ track_description.get('en', '')|safe }}
                         </div>
                     </div>
                     {% endif %}