Fix openvidu-live-captions null pointer

ai-services/openvidu-live-captions/src/app.js

@@ -63,11 +63,20 @@ async function joinRoom() {
     const trackId = reader.info.attributes["lk.transcribed_track_id"];
 
     if (isFinal) {
-        const speaker = participantInfo.identity == room.localParticipant.identity
+      // Due to a bug in LiveKit Server the participantInfo object may be empty.
-            ? "You" : participantInfo.identity;
+      // You can still get the participant owning the audio track like below:
-        const timestamp = new Date().toLocaleTimeString();
+      let participant;
+      if (room.localParticipant.audioTrackPublications.has(trackId)) {
+        participant = room.localParticipant;
+      } else {
+        participant = room.remoteParticipants.values().find(p => p.audioTrackPublications.has(trackId));
+      }
+
       const captionsTextarea = document.getElementById("captions");
-        captionsTextarea.value += `[${timestamp}] ${speaker}: ${message}\n`;
+      const timestamp = new Date().toLocaleTimeString();
+      const participantIdentity =
+        participant == room.localParticipant ? "You" : participant.identity;
+      captionsTextarea.value += `[${timestamp}] ${participantIdentity}: ${message}\n`;
       captionsTextarea.scrollTop = captionsTextarea.scrollHeight;
     }
   }
@@ -91,7 +100,7 @@ async function joinRoom() {
 
     // Publish your camera and microphone
     await room.localParticipant.enableCameraAndMicrophone();
-    const localVideoTrack = this.room.localParticipant.videoTrackPublications
+    const localVideoTrack = room.localParticipant.videoTrackPublications
       .values()
       .next().value.track;
     addTrack(localVideoTrack, userName, true);