message: Live location sharing: fix code smells - return useEffect unsub, dont map
diff: @@ -68,13 +68,13 @@ const useLivenessMonitor = (liveBeaconIds: BeaconIdentifier[], beacons: Map<Beac
  // refresh beacon monitors when the tab becomes active again
  const onPageVisibilityChanged = () => {
  if (document.visibilityState === 'visible') {
  - liveBeaconIds.map(identifier => beacons.get(identifier)?.monitorLiveness());
  + liveBeaconIds.forEach(identifier => beacons.get(identifier)?.monitorLiveness());
  }
  };
  if (liveBeaconIds.length) {
  document.addEventListener("visibilitychange", onPageVisibilityChanged);
  }
  - () => {
  + return () => {
  document.removeEventListener("visibilitychange", onPageVisibilityChanged);
  };
  }, [liveBeaconIds, beacons]);
  