group call MediaStream has been disposed. error

[hdev72]

I thought this group chat worked well, but after a successful group connection, when a user leaves the room, another user receives the error, (like my own Android project).

error:
2022-05-13 18:51:46.335 31878-2900/com.dds.webrtc.debug E/AndroidRuntime: FATAL EXCEPTION: pool-33-thread-1
Process: com.dds.webrtc.debug, PID: 31878
java.lang.IllegalStateException: MediaStream has been disposed.
at org.webrtc.MediaStream.checkMediaStreamExists(MediaStream.java:134)
at org.webrtc.MediaStream.getNativeMediaStream(MediaStream.java:128)
at org.webrtc.PeerConnection.addStream(PeerConnection.java:909)
at com.dds.skywebrtc.engine.webrtc.Peer.addLocalStream(Peer.java:101)
at com.dds.skywebrtc.engine.webrtc.WebRTCEngine.userIn(WebRTCEngine.java:148)
at com.dds.skywebrtc.AVEngine.userIn(AVEngine.java:53)
at com.dds.skywebrtc.CallSession.lambda$newPeer$11$com-dds-skywebrtc-CallSession(CallSession.java:267)
at com.dds.skywebrtc.CallSession$$ExternalSyntheticLambda21.run(Unknown Source:4)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
at java.lang.Thread.run(Thread.java:784)