fix panic on close channel (#495)

pkg/rtc/participant.go

@@ -1518,7 +1518,7 @@ func (p *ParticipantImpl) hasPendingMigratedTrack() bool {
 }
 
 func (p *ParticipantImpl) onUpTrackManagerClose() {
-	close(p.rtcpCh)
+	p.rtcpCh <- nil
 }
 
 func (p *ParticipantImpl) getPendingTrack(clientId string, kind livekit.TrackType) (string, *livekit.TrackInfo) {

pkg/sfu/receiver.go

@@ -380,7 +380,11 @@ func (w *WebRTCReceiver) sendRTCP(packets []rtcp.Packet) {
 		return
 	}
 
-	w.rtcpCh <- packets
+	select {
+	case w.rtcpCh <- packets:
+	default:
+		w.logger.Warnw("sendRTCP failed, rtcp channel full", nil)
+	}
 
 	for _, p := range packets {
 		switch pkt := p.(type) {