Ensure ethstats plugin handles incorrect server responses

Author: cburgdorf

trinity/plugins/builtin/ethstats/ethstats_client.py

@@ -59,7 +59,7 @@ async def recv_handler(self) -> None:
             try:
                 message: EthstatsMessage = self.deserialize_message(json_string)
             except EthstatsException as e:
-                self.logger.info('Cannot parse message from server: %s' % e)
+                self.logger.warning('Cannot parse message from server: %s' % e)
                 return
 
             await self.recv_queue.put(message)
@@ -84,6 +84,9 @@ def deserialize_message(self, json_string: str) -> EthstatsMessage:
         except json.decoder.JSONDecodeError as e:
             raise EthstatsException('Received incorrect JSON: %s' % e)
 
+        if isinstance(raw_message, str):
+            raise EthstatsException(f'Received invalid payload: {raw_message}')
+
         try:
             payload = raw_message['emit']
         except KeyError: