fix bug in multi-group peer registration

src/bin/mgen-peer.rs

@@ -359,7 +359,13 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                 user_recipient_map.insert(recipient.name.clone(), for_io);
                 state_to_writer
             } else {
-                user_recipient_map[&recipient.name].state_to_writer.clone()
+                let for_io = user_recipient_map.get_mut(&recipient.name).unwrap();
+                if !for_io.reader_to_states.contains_key(&config.group) {
+                    for_io
+                        .reader_to_states
+                        .insert(config.group.clone(), reader_to_state.clone());
+                }
+                for_io.state_to_writer.clone()
             };
             conversation_recipient_map.insert(
                 recipient.name.clone(),