Merge pull request '#138 Bugfix' (#167) from 138_New_map_client into master

Reviewed-on: SGD-Nord/konova#167

konova/forms.py

@@ -311,6 +311,9 @@ class SimpleGeomForm(BaseForm):
 
         # Get geojson from form
         geom = self.data["geom"]
+        if geom is None or len(geom) == 0:
+            # empty geometry is a valid geometry
+            return is_valid
         geom = json.loads(geom)
 
         # Write submitted data back into form field to make sure invalid geometry