Check for data

personal_data/fetchers/partisia_blockchain.py

@@ -40,7 +40,11 @@ class MpcBalance(Scraper):
         response = self.session.post(url, headers = headers, data=json.dumps(data))
         response.raise_for_status()
         date = response.headers.get('last-modified') or response.headers.get('date')
-        return response.json(), date
+        json_data = response.json()
+        if json_data is None:
+            msg = 'No result data for ' + url
+            raise Exception(msg)
+        return json_data, date
 
     def determine_coins(self) -> list[dict]:
         data: dict = {'path':[]}