fetchUser = async (userId) => {
  if (config.APP_ENV !== 'production') return new User(mockUsers[userId]);
  try {
    const { data } = await fetchProfile({ userId });
    return new User(data);
  } catch {
    return new User({ displayName: t('__SOURCE_NAME_SOMEONE') });
  }
}
@param {string} userId
@returns {Promise<User>}