[experiments] Only show output of blocks when they are done

beat/web/experiments/templates/experiments/view.html

@@ -255,6 +255,7 @@
                       </ul>
                     </li>
                     {% endif %}
+                    {% if block.done %}
                     {% if error_report %}
                     <li>Captured Errors (on user code):
                       <pre class="console-output">{{ error_report }}</pre>
@@ -270,6 +271,7 @@
                       <pre class="console-output">{{ block.stderr }}</pre>
                     </li>
                     {% endif %}
+                    {% endif %}{# block.done #}
                   </ul>
                 </div>{# panel body #}
               </div>{# collapse #}