vm: handle node.driver_version errors

circle/dashboard/templates/dashboard/node-detail/resources.html

@@ -12,11 +12,13 @@
     <dt>{% trans "Priority" %}:</dt><dd>{{ node.priority }}</dd>
     <dt>{% trans "Driver Version:" %}</dt>
     <dd>
+      {% if node.driver_version %}
         {{ node.driver_version.branch }} at
         {{ node.driver_version.commit }} ({{ node.driver_version.commit_text }})
         {% if node.driver_version.is_dirty %}
           <span class="label label-danger">{% trans "with uncommitted changes!" %}</span>
         {% endif %}
+      {% endif %}
     </dd>
     <dt>{% trans "Host owner" %}:</dt>
     <dd>

circle/vm/models/node.py

@@ -291,7 +291,7 @@ class Node(OperatedMixin, TimeStampedModel):
     @property
     @node_available
     def driver_version(self):
-        return self.info['driver_version']
+        return self.info.get('driver_version')
 
     @property
     @node_available