Call safeToRemove After Async Work

When using usePresence, always call safeToRemove after async work.

Incorrect (missing safeToRemove):

function AsyncComponent() {
  const [isPresent, safeToRemove] = usePresence();

  useEffect(() => {
    if (!isPresent) {
      cleanup();
    }
  }, [isPresent]);
}

Correct (safeToRemove called):

function AsyncComponent() {
  const [isPresent, safeToRemove] = usePresence();

  useEffect(() => {
    if (!isPresent) {
      cleanup().then(safeToRemove);
    }
  }, [isPresent, safeToRemove]);
}