bug fix with plans

src/api/store.py

@@ -396,7 +396,7 @@ class Plans(Store) :
         :email  user's email
         :id     plan id (optional) will default to free plan
         """
-        free_plan = [item['id'] for item in self.plans if item['amount'] == 0]
+        free_plan = [item['id'] for item in self.plans if 'amount' in item and item['amount'] == 0]
         if free_plan :
             free_plan = free_plan[0]
         # id = args['id'] if 'id' in args else free_plan