Strictify voice-broadcast (#10393)

src/voice-broadcast/hooks/useVoiceBroadcastRecording.tsx

@@ -1,5 +1,5 @@
 /*
-Copyright 2022 The Matrix.org Foundation C.I.C.
+Copyright 2022-2023 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -66,6 +66,12 @@ export const useVoiceBroadcastRecording = (
         throw new Error("Unable to find voice broadcast room with Id: " + roomId);
     }
 
+    const sender = recording.infoEvent.sender;
+
+    if (!sender) {
+        throw new Error(`Voice Broadcast sender not found (event ${recording.infoEvent.getId()})`);
+    }
+
     const stopRecording = async (): Promise<void> => {
         const confirmed = await showStopBroadcastingDialog();
 
@@ -99,7 +105,7 @@ export const useVoiceBroadcastRecording = (
         timeLeft,
         recordingState,
         room,
-        sender: recording.infoEvent.sender,
+        sender,
         stopRecording,
         toggleRecording: recording.toggle,
     };