Don't panic if the server sends something unexpected

I mean, it *is* a different version.

src/client/mod.rs

@@ -197,7 +197,7 @@ async fn client_handle_messages<T: AsyncRead + Unpin>(
                     // TODO: Log
                 }
             }
-            message => panic!("Unsupported: {:?}", message),
+            message => error!("Unsupported: {:?}", message),
         };
     }
 }