Unhandled Exception: type 'Null' is not a subtype of type 'String'

[XuanTung95]

Your environment.

• Version: ion-sdk-flutter v0.4.4, ion v1.9.0

What did you do?

• Run ion-app-flutter

What happened?

Got this error after connected to room

I/flutter (30576): Get Message: {"receiver":{"receiverId":"f91130c6-6267-4936-a17d-85e769ab959b","rtpParameters":{"headerExtensions":[],"encodings":[],"codecs":[],"rtcp":{"cname":"","reducedSize":false},"transactionId":""},"track":{"kind":"audio","readyState":"LIVE","id":"f91130c6-6267-4936-a17d-85e769ab959b","label":"audio","enabled":true}},"sender":{"senderId":"6dd4c311-e253-401d-855a-2dc1dad942e4","rtpParameters":{"headerExtensions":[],"encodings":[],"codecs":[],"rtcp":{"cname":"","reducedSize":false},"transactionId":"fde3c233-2440-4572-a464-a9def316915c"},"ownsTrack":true,"track":{"kind":"audio","readyState":"LIVE","id":"6dd4c311-e253-401d-855a-2dc1dad942e4","label":"audio","enabled":true},"dtmfSender":{"duration":100,"dtmfSenderId":"6dd4c311-e253-401d-855a-2dc1dad942e4","interToneGap":50}},"mid":null,"transceiverId":null,"direction":"sendonly"}
E/flutter (30576): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: type 'Null' is not a subtype of type 'String'
E/flutter (30576): #0      new RTCRtpTransceiverNative.fromMap (package:flutter_webrtc/src/native/rtc_rtp_transceiver_impl.dart:74:12)
E/flutter (30576): #1      RTCPeerConnectionNative.addTransceiver (package:flutter_webrtc/src/native/rtc_peerconnection_impl.dart:512:38)
E/flutter (30576): <asynchronous suspension>
E/flutter (30576): #2      LocalStream.publishTrack (package:flutter_ion/src/stream.dart:236:27)
E/flutter (30576): <asynchronous suspension>
E/flutter (30576): 
I/flutter (30576): Get Message: {"receiver":{"receiverId":"a1a646a8-6c89-48e0-baae-5138dc8c57f2","rtpParameters":{"headerExtensions":[],"encodings":[],"codecs":[],"rtcp":{"cname":"","reducedSize":false},"transactionId":""},"track":{"kind":"video","readyState":"LIVE","id":"a1a646a8-6c89-48e0-baae-5138dc8c57f2","label":"video","enabled":true}},"sender":{"senderId":"a4512cfe-12c4-4986-bf11-6b7ba02dd282","rtpParameters":{"headerExtensions":[],"encodings":[{"active":true,"maxBitrate":2500000,"numTemporalLayers":1,"scaleResolutionDownBy":1.0,"maxFramerate":30}],"codecs":[],"rtcp":{"cname":"","reducedSize":false},"transactionId":"3770804e-3a45-41a4-852e-0d1f5eab7a45"},"ownsTrack":true,"track":{"kind":"video","readyState":"LIVE","id":"a4512cfe-12c4-4986-bf11-6b7ba02dd282","label":"video","enabled":true},"dtmfSender":{"dtmfSenderId":"a4512cfe-12c4-4986-bf11-6b7ba02dd282"}},"mid":null,"transceiverId":null,"direction":"sendonly"}
E/flutter (30576): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: type 'Null' is not a subtype of type 'String'
E/flutter (30576): #0      new RTCRtpTransceiverNative.fromMap (package:flutter_webrtc/src/native/rtc_rtp_transceiver_impl.dart:74:12)
E/flutter (30576): #1      RTCPeerConnectionNative.addTransceiver (package:flutter_webrtc/src/native/rtc_peerconnection_impl.dart:512:38)
E/flutter (30576): <asynchronous suspension>
E/flutter (30576): #2      LocalStream.publishTrack (package:flutter_ion/src/stream.dart:236:27)
E/flutter (30576): <asynchronous suspension>
E/flutter (30576): 

I think the problems might relate to this block of code:

  void join(String sid, String uid) async {
    try {
      transports[RoleSub]!.pc!.onTrack = (RTCTrackEvent ev) {
        var remote = makeRemote(ev.streams[0], transports[RoleSub]!);
        ontrack?.call(ev.track, remote);
      };

      var pc = transports[RolePub]!.pc;
      if (pc != null) {
        var offer = await pc.createOffer({});
        await pc.setLocalDescription(offer);
        print('Step 1');
        var answer = await signal.join(sid, uid, offer);
        print('Step 2');                                         <-------- This line is never called
        await pc.setRemoteDescription(answer);
        transports[RolePub]!.hasRemoteDescription = true;
        transports[RolePub]!.candidates.forEach((c) => pc.addCandidate(c));
        pc.onRenegotiationNeeded = () => onnegotiationneeded();
      }
    } catch (e) {
      print('join: e => ${e.toString()}');
    }
  }

[jazzyyoung]

i have got the same problem :(

[ChokWah]

I have got the same problem....

And, stream.preferLayer!(ion.Layer.medium); can's show camera view is screen? how to show camera view is screen?