failed to set session description

[devgohel8520]

Hi,
I want to say thanks first. It saved lots of time of mine.

If you can help me to get rid out of this.

I clone your code and it is working fine when I make call on web based(peerjs heroku app) platform but the only problem when I received call from web app which is saying "failed to set session description".

I am getting offer code and that run perfactly but after oncall i am getting this below error:
this is what i am getting on console:
2017-09-09 19:24:06.772481+0530 PeerObjectiveC[665:156448] Failed to set session description. Error: Error Domain=RTCSDPError Code=-1 "(null)" UserInfo={error=SessionDescription is NULL.}
2017-09-09 19:24:06.772661+0530 PeerObjectiveC[665:156448] disconnecting....
2017-09-09 19:24:06.772737+0530 PeerObjectiveC[665:156448] deleteRemoteMediaStream
2017-09-09 19:24:06.772806+0530 PeerObjectiveC[665:156448] deleteLocalMediaStream
2017-09-09 19:24:06.773257+0530 PeerObjectiveC[665:156703] WARNING: Renegotiation needed but unimplemented.
2017-09-09 19:24:06.773618+0530 PeerObjectiveC[665:156448] local video audio track remove from media stream
2017-09-09 19:24:06.774098+0530 PeerObjectiveC[665:156448] onError: Error Domain=PeerJS Code=-4 "Failed to set session description." UserInfo={NSLocalizedDescription=Failed to set session description.}