where we can not extract any message_seq for piggybacking. BUG=webrtc:367395350 Change-Id: I2e42d3b1304b5cf204c34bc8a136f17c363e011c Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/372881 Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Jonas Oreland <jonaso@webrtc.org> Commit-Queue: Jonas Oreland <jonaso@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43731}