🐛(frontend) omit the default speaker id sent to LiveKit

Fix Firefox setSinkId('default') errors by omitting 'default'; only set real device IDs.

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to
 
 ### Fixed
 
+- 🐛(frontend) omit the default speaker id sent to LiveKit
 - 🐛(frontend) enforce recording-mode permissions on the checkboxes
 - 🔒️(agents) fix util-linux CVEs reported by Cyberwatch
 

src/frontend/src/features/analytics/exceptionFilters.ts

@@ -8,6 +8,10 @@ const IGNORED_EXCEPTION_PATTERNS = [
   // the close reason is already logged by the SDK.
   // See: https://github.com/livekit/client-sdk-js/issues/2062
   /^Event captured as exception with keys: isTrusted$/,
+  // LiveKit logs a rejected setSinkId on remote audio attach and already
+  // swallows it. capture_console_errors turns that log into an exception
+  // and stringifies the real error as [object Object].
+  /^Failed to set sink id on remote audio track/,
 ]
 
 const shouldIgnoreException = (value: unknown): boolean =>

src/frontend/src/features/rooms/components/Conference.tsx

@@ -45,6 +45,7 @@ import { userStore } from '@/stores/user'
 import { WatchMediaDeviceErrors } from './WatchMediaDeviceErrors'
 import { MeetDevtools } from '@/features/devtools'
 import { VOICE_AUDIO_CONSTRAINTS } from '@/features/rooms/livekit/utils/constants'
+import { resolveAudioOutputDeviceId } from '@/features/rooms/utils/resolveAudioOutputDeviceId'
 
 export const Conference = ({
   roomId,
@@ -120,7 +121,7 @@ export const Conference = ({
         ...VOICE_AUDIO_CONSTRAINTS,
       },
       audioOutput: {
-        deviceId: userConfig.audioOutputDeviceId ?? undefined,
+        deviceId: resolveAudioOutputDeviceId(userConfig.audioOutputDeviceId),
       },
     }
     // do not rely on the userConfig object directly as its reference may change on every render

src/frontend/src/features/rooms/utils/resolveAudioOutputDeviceId.ts

@@ -0,0 +1,11 @@
+/**
+ * `'default'` means "use the system output". Firefox has no device with that
+ * id, so LiveKit's setSinkId('default') rejects on every remote audio attach.
+ * Omit it and the browser keeps the OS default, which is the same result.
+ */
+export const resolveAudioOutputDeviceId = (
+  deviceId: string | undefined
+): string | undefined => {
+  if (!deviceId || deviceId === 'default') return undefined
+  return deviceId
+}