[typeOrm]leftJoin시 주의할점

case1

const pushes = await pushRepo
        .createQueryBuilder('push')
        .select('push.push_id')
        .addSelect('other_profile.user_profile_img')
        .leftJoin('push.other_user', 'other_user')
        .leftJoin('other_user.profile', 'other_profile')
        .where('push.receiver = :receiver', { receiver: userId })
        .orderBy('push.created_at', 'DESC')
        .getMany();

case2

const pushes = await pushRepo
        .createQueryBuilder('push')
        .select('push.push_id')
        .addSelect('other_user.id')  <===
        .addSelect('other_profile.user_profile_img')
        .leftJoin('push.other_user', 'other_user')
        .leftJoin('other_user.profile', 'other_profile')
        .where('push.receiver = :receiver', { receiver: userId })
        .orderBy('push.created_at', 'DESC')
        .getMany();

leftJoin시 해당 엔티티의 아이디를 select하지 않으면 해당 엔티티의 다른 값을 가져올 수 없다.