base adresse: return a "bad request" if it's missing parameters (#8544)

passerelle/apps/base_adresse/views.py

@@ -3,7 +3,7 @@ import urllib
 import urlparse
 
 from django.core.urlresolvers import reverse
-from django.http import Http404
+from django.http import Http404, HttpResponseBadRequest
 from django.shortcuts import redirect
 from django.views.generic.base import View, RedirectView
 from django.views.generic.detail import SingleObjectMixin, DetailView
@@ -69,6 +69,10 @@ class ReverseView(View, SingleObjectMixin):
             response_format = request.GET['format']
         if response_format != 'json':
             raise NotImplementedError()
+
+        if not 'lat' in request.GET or not 'lon' in request.GET:
+            return HttpResponseBadRequest('missing parameter')
+
         lat = request.GET['lat']
         lon = request.GET['lon']