fix: disconnect reason inconsistent. (#715)

Author: cloudwebrtc

lib/src/core/engine.dart

@@ -991,7 +991,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
       logger.fine('Signal disconnected ${event.reason}');
       if (event.reason == DisconnectReason.disconnected && !_isClosed) {
         await handleDisconnect(ClientDisconnectReason.signal);
-      } else {
+      } else if (event.reason == DisconnectReason.signalingConnectionFailure) {
         events.emit(EngineDisconnectedEvent(
           reason: event.reason,
         ));

lib/src/core/room.dart

@@ -601,7 +601,7 @@ class Room extends DisposableChangeNotifier with EventsEmittable<RoomEvent> {
   Future<void> disconnect() async {
     if (engine.isClosed &&
         engine.connectionState == ConnectionState.disconnected) {
-      events.emit(RoomDisconnectedEvent(reason: DisconnectReason.unknown));
+      logger.warning('Engine is already closed');
       return;
     }
     await engine.disconnect();

lib/src/core/signal_client.dart

@@ -79,6 +79,7 @@ class SignalClient extends Disposable with EventsEmittable<SignalEvent> {
 
     onDispose(() async {
       await cleanUp();
+      await events.cancelAll();
       await events.dispose();
       if (!kIsWeb && !lkPlatformIsTest()) {
         await _connectivitySubscription?.cancel();