[Bug] Não está funcionando

Exception in thread "main" javax.persistence.RollbackException: Error while committing the transaction
at org.hibernate.internal.ExceptionConverterImpl.convertCommitException(ExceptionConverterImpl.java:81)
at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:104)
at br.com.alura.alugames.dados.DAO.adicionar(DAO.kt:19)
at br.com.alura.alugames.principal.TesteGamerBancoKt.main(testeGamerBanco.kt:17)
at br.com.alura.alugames.principal.TesteGamerBancoKt.main(testeGamerBanco.kt)
Caused by: java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : br.com.alura.alugames.dados.GamerEntity.plano -> br.com.alura.alugames.dados.PlanoEntity
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:151)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188)
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1395)
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:482)
at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3274)
at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2409)
at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:449)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:183)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$300(JdbcResourceLocalTransactionCoordinatorImpl.java:40)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:281)
at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:101)
... 3 more
Caused by: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : br.com.alura.alugames.dados.GamerEntity.plano -> br.com.alura.alugames.dados.PlanoEntity
at org.hibernate.engine.spi.CascadingActions$8.noCascade(CascadingActions.java:379)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:169)
at org.hibernate.event.internal.AbstractFlushingEventListener.cascadeOnFlush(AbstractFlushingEventListener.java:159)
at org.hibernate.event.internal.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:149)
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:82)
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107)
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1391)
... 11 more