rethinkdb upsert

    try {
      await UserSession.get(ctx.id).update({ pingedAt: r.now() }, { durability: 'soft' });
    } catch (e) {
      if (e.name === 'DocumentNotFoundError') {
        await UserSession
          .insert({ id: ctx.id, userId: ctx.user.id, pingedAt: r.now() }, { durability: 'soft' });
      } else {
        log.error(`Failed to update user session ${ctx.id}`, {
          error: err
        });
      }
    }