#42: fix it in django as well

Author: chfw

pyexcel_io/database/importers/django.py

@@ -82,4 +82,6 @@ def create_sheet(self, sheet_name):
             sheet_writer = DjangoModelWriter(
                 self.__importer, model,
                 batch_size=self._keywords.get('batch_size', None))
+        else:
+            raise Exception("No django model found!")
         return sheet_writer