[Flutter] - SessionDescription is NULL

Hi everyone, I use mediasoup_client_flutter for flutter app, i’m getting this error when send sdp. Can anyone help me how to fix it. Thanks. (Sorry my english is not good).

[answer:{sdp: v=0
    o=mediasoup-client 10000 1 IN IP4 0.0.0.0
    s=-
    t=0 0
    a=ice-lite
    a=fingerprint:sha-512 65:F0:4D:B4:75:39:14:0A:B7:C8:EE:38:2B:81:1D:CA:91:3A:22:6F:3A:57:1B:57:A3:D5:07:41:8C:01:B6:49:16:75:4E:B7:66:DF:5F:E8:0A:EF:94:37:2E:9C:1C:10:A4:1C:91:98:26:C5:28:D6:3A:F1:A2:81:68:1A:22:0B
    a=msid-semantic: WMS *
    a=group:BUNDLE 0
    m=audio 7 UDP/TLS/RTP/SAVPF 111
    c=IN IP4 127.0.0.1
    a=rtpmap:111 opus/48000/2
    a=fmtp:111 stereo=1;useinbandfec=0;usedtx=1
    a=rtcp-fb:111 transport-cc 
    a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
    a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
    a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
    a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
    a=setup:active
    a=mid:0
    a=recvonly
    a=ice-ufrag:eoqgj4l291hgy9cm
    a=ice-pwd:3x350xan2amdjelboage5arw7fb6kj2w
    a=candidate:tcpcandidate 1 udp 1076302079 103.170.246.155 50566 typ host

Log Error: peerConnectionSetRemoteDescription(): WEBRTC_SET_REMOTE_DESCRIPTION_ERROR: SessionDescription is NULL.