Fix get_css_classes on new default tops without localtops

/close #195

templates/protocol-tops-include.html

@@ -4,18 +4,20 @@
         {% for default_top in protocol.protocoltype.default_tops %}
             {% if not default_top.is_at_end() %}
                 {% set localtop = default_top.get_localtop(protocol) %}
-                <li class="{{localtop.get_css_classes()|join(" ")}}" {% if localtop.is_expandable() %} id="localtop-{{localtop.id}}" title="{{localtop.description}}"{% endif %}>
-                    {{default_top.name}}
-                    {% if not protocol.is_done() and has_modify_right %}
-                        <a href="{{url_for('edit_localtop', localtop_id=localtop.id)}}">Ändern</a>
-                    {% endif %}
-                    {% if has_private_view_right and localtop.description is not none and localtop.description|length > 0 %}
-                        <span class="glyphicon glyphicon-info-sign"></span>
-                        <pre id="localtop-{{localtop.id}}-description" class="expansion-text">
-                            {{-localtop.description-}}
-                        </pre>
-                    {% endif %}
-                </li>
+                {% if localtop is not none %}
+                  <li class="{{localtop.get_css_classes()|join(" ")}}" {% if localtop.is_expandable() %} id="localtop-{{localtop.id}}" title="{{localtop.description}}"{% endif %}>
+                      {{default_top.name}}
+                      {% if not protocol.is_done() and has_modify_right %}
+                          <a href="{{url_for('edit_localtop', localtop_id=localtop.id)}}">Ändern</a>
+                      {% endif %}
+                      {% if has_private_view_right and localtop.description is not none and localtop.description|length > 0 %}
+                          <span class="glyphicon glyphicon-info-sign"></span>
+                          <pre id="localtop-{{localtop.id}}-description" class="expansion-text">
+                              {{-localtop.description-}}
+                          </pre>
+                      {% endif %}
+                  </li>
+                {% endif %}
             {% endif %}
         {% endfor %}
     {% endif %}