No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call

해결방법

1. @Transactional 어노테이션 추가

@Transactional
    public String save(Member member) {
        // memberTable.put(member.getUserId(), member);
        entityManager.persist(member);

        // Member savedMember =  memberTable.get(member.getUserId());
        Member savedMember = entityManager.find(Member.class, member.getId());
        System.out.println("/users : repository - " + savedMember);
        return savedMember.getUserId();
    }

참고자료
https://velog.io/@sunaookamisiroko/No-EntityManager-with-actual-transaction-available-for-current-thread-cannot-reliably-process-remove-call-%EC%97%90%EB%9F%AC..-%EC%BB%A4%EC%8A%A4%ED%85%80-%EB%A9%94%EC%84%9C%EB%93%9C