Catch exception if we got an unknown response from OpenStack

If we are getting an unexpected reponse from OpenStack we should not
fail, but render a 500 error to the client

ooi/api/base.py

@@ -18,8 +18,11 @@
 
 from ooi import utils
 
+from oslo_log import log as logging
 import webob.exc
 
+LOG = logging.getLogger(__name__)
+
 
 class Controller(object):
     def __init__(self, app, openstack_version):
@@ -102,7 +105,12 @@ def exception_from_response(response):
         503: webob.exc.HTTPServiceUnavailable,
     }
     code = response.status_int
-    message = response.json_body.popitem()[1].get("message")
+    try:
+        message = response.json_body.popitem()[1].get("message")
+    except Exception:
+        LOG.exception("Unknown error happenened processing response %s"
+                      % response)
+        return webob.exc.HTTPInternalServerError
 
     exc = exceptions.get(code, webob.exc.HTTPInternalServerError)
     return exc(explanation=message)