set proto only if it was given

src/treepuncher/treepuncher.py

@@ -239,6 +239,7 @@ class Treepuncher(
 	async def _work(self):
 		try:
 			server_data = await self.info()
+			if "version" in server_data and "protocol" in server_data["version"]:
 				self.dispatcher.set_proto(server_data['version']['protocol'])
 		except Exception:
 			return self.logger.exception("exception while pinging server")