Unknown DataChannel error logged as console.error for graceful close events (audio-only rooms)

[ECREedukacja]

Describe the bug

What I'm expecting

Joining and leaving an audio-only room (<LiveKitRoom video={false} audio={true} ...>) should not log console.error lines when no actual error has occurred.

What happens instead

On every room leave / route change, Unknown DataChannel error on lossy and/or Unknown DataChannel error on reliable is logged at error severity. The underlying browser event is a generic Event (not ErrorEvent) emitted during graceful close / ICE restart cleanup — event.message and event.error are undefined. There is no actual failure; audio works correctly. But the red console.error lines:

• Get flagged by error-tracking tools (Sentry / Datadog RUM) as production errors
• Confuse developers reviewing console output
• Have no diagnostic value (payload { event } contains no usable information)

Code location

src/room/RTCEngine.ts:996-1006:

private handleDataError = (event: Event) => {
  const channel = event.currentTarget as RTCDataChannel;
  const channelKind = channel.maxRetransmits === 0 ? 'lossy' : 'reliable';

  if (event instanceof ErrorEvent && event.error) {
    const { error } = event.error;
    this.log.error(`DataChannel error on ${channelKind}: ${event.message}`, { error });
  } else {
    this.log.error(`Unknown DataChannel error on ${channelKind}`, { event });  // ← issue
  }
};

The else branch fires when event is NOT an ErrorEvent with event.error populated — i.e. there is no actual error data, yet it is logged at error severity.

Proposed fix

Downgrade else branch from log.error to log.debug (one-line diff):

   } else {
-    this.log.error(`Unknown DataChannel error on ${channelKind}`, { event });
+    this.log.debug(`Unknown DataChannel error on ${channelKind}`, { event });
   }

Rationale:

• Real errors (with event.error populated) still take the if branch — unaffected
• log.debug is invisible by default but available via setLogLevel('debug') for users actively debugging data channels
• Zero behavioral change — only severity adjustment of an informational log

Reproduction

1. Create a minimal audio-only room with livekit-client 2.19.0:

import { Room } from 'livekit-client';

const room = new Room();
await room.connect(serverUrl, token);
await room.localParticipant.setMicrophoneEnabled(true);
// ... use room for a bit ...
await room.disconnect();

Or, equivalently, using @livekit/components-react:

<LiveKitRoom token={token} serverUrl={url} video={false} audio={true} connect>
  <RoomAudioRenderer />
</LiveKitRoom>

2. Trigger a leave (room.disconnect(), route change, or component unmount).
3. Observe DevTools Console — red Unknown DataChannel error on lossy / Unknown DataChannel error on reliable lines appear.

Reproduces consistently across Chrome 130 / Firefox 132 / Safari 18 (tested) on every leave.

Logs

Unknown DataChannel error on lossy
  at HTMLDocument.<anonymous> (livekit-client.esm.mjs:21183)
  ...
Unknown DataChannel error on reliable
  at HTMLDocument.<anonymous> (livekit-client.esm.mjs:21183)
  ...

Payload object (when inspected): { event: Event { isTrusted: true, type: 'error', target: RTCDataChannel } } — no message, no error, no stack beyond the SDK's own log call site.

System Info

  System:
    OS: macOS 12.6.3
    CPU: (4) x64 Intel(R) Core(TM) i5-5250U CPU @ 1.60GHz
    Memory: 40.92 MB / 4.00 GB
    Shell: 3.2.57 - /bin/bash
  Binaries:
    Node: 24.15.0 - /usr/local/bin/node
    npm: 11.12.1 - /usr/local/bin/npm
  Browsers:
    Brave Browser: 110.1.48.171
    Safari: 17.6
  npmPackages:
    @livekit/components-react: ^2.9.21 => 2.9.21
    livekit-client: ^2.19.0 => 2.19.0
    livekit-server-sdk: ^2.15.3 => 2.15.3

Also reproduced on Chrome 130 and Firefox 132 (separate test machine).

Severity

annoyance

Additional Information

Workarounds attempted (none satisfactory)

1. setLogExtension (Sentry-style log forwarding) — only forwards logs downstream, does not filter or suppress upstream console.error.
2. setLogLevel('warn') on the engine logger — silences all errors, too broad.
3. RoomOptions.logger / custom logger injection — not in stable public API.
4. Avoid creating data channels when video: false — RTCEngine.createDataChannels() (line 827) is called unconditionally regardless of published media tracks.
5. Override console.error globally — works but global side effect, fragile, breaks other error tooling.
6. patch-package with the proposed one-line diff — current workaround in our project (Next.js 16 + React 19, audio-only tutoring app); applied at build time via postinstall.

Willing to submit PR

Yes — happy to open a PR with the one-line diff above if maintainers agree on the approach. Open to alternative approaches (e.g. add an option to silence specific log categories) if preferred.

[1egoman]

@ECREedukacja Hi! Thanks for the detailed error report - I'm not a fan of just sliencing the log, I'd much rather figure out what the actual cause of it is.

I have been unable to reproduce this scenario locally, but looking at the code, I have a suspicion what might be going on and have attempted a fix in #1978. Would you be able to give this a try and see if the log is no longer visible?