undefined participant.trackPublications

[tobowers]

Select which package(s) are affected

@livekit/rtc-node

Describe the bug

Uncaught exception detected: undefined is not an object (evaluating 'participant.trackPublications'

We see this sometimes (actually quite often) in our @livekit/node-rtc server side. We are waiting for the remote participant, and it joins (we see it join in the web client), but this error is triggered and we never see it in the remoteParticipants (even 10s later or so). It's triggered a few times in a row.

Reproduction

not sure how to reliably do this, but it happens very often where are :

Creating a new room, having node-rtc client connect and the unity client connect. The error is happening below our code.

Logs

error: Uncaught exception detected: undefined is not an object (evaluating 'participant.trackPublications') {"alert":true,"error":{"message":"undefined is not an object (evaluating 'participant.trackPublications')"},"errorCount":1,"timestamp":"2025-05-07T09:11:50.704Z"}

System Info

bun 1.2.9
rtc-node 0.13.12

LiveKit server version

LiveKit cloud

Severity

serious, but I can work around it

Additional Information

No response

[tobowers]

tracked it down to this line:

node-sdks/packages/livekit-rtc/src/room.ts

Line 267 in 266add8

participant!.trackPublications.set(publication.sid!, publication);

And I'm noticing that I'm getting the track published event but not the participant connected event.

It appears that there's a race between the room connecting and getting the participants and then listening for a new participant?