Presence diff do not get updated because of inPendingSyncState is false

[jaybe78]

Hello,

I'm not sure whether this is a bug or not but this line https://github.com/braverhealth/phoenix-socket-dart/blob/master/lib/src/presence.dart#L123

only sets channelRef for "presence_state" events

Presence.dart

  void _onMessage(Message message) {
    if (message.event.value == stateEventName) {
      _joinRef = channel.joinRef;

Consequently, the diff events do not always get sent to the onSync callback, which is a problem because I end up having inconsistent list of users when I test...

For example backend side:

def handle_info(%Phoenix.Socket.Broadcast{topic: topic, event: "presence_diff", payload: payload}, socket) do
   push(socket, "presence_diff", payload)
    {:noreply, socket}
  end

 if (inPendingSyncState) {
        pendingDiffs.add(diff);
      }

I don't really understand what that test if for but what I tried is to move the lift up the setting of the channelRef

void _onMessage(Message message) {
   _joinRef = channel.joinRef;
    // Processing of 'state' events.
    if (message.event.value == stateEventName) {
     
      final newState = _decodeStateFromPayload(message.payload!);
      state = _syncState(state, newState);
      for (final diff in pendingDiffs) {
        state = _syncDiff(state, diff);
      }
      pendingDiffs = [];
      onSync();

      // Processing of 'diff' events.
    } else if (message.event.value == diffEventName) {
       // added line
      _joinRef = channel.joinRef;
      final diff = _decodeDiffFromPayload(message.payload!);
      if (inPendingSyncState) {
        pendingDiffs.add(diff);
      } else {
        state = _syncDiff(state, diff);
        onSync();
      }
    }
  }

Doing so I get all diff updates correctly sent to presence.onMessage callback