问题：
在Spring Boot中使用JpaRepository的deleteById(ID id)方法删除数据时，首先要使用existsById(ID id)方法判断数据是否存在。如果存在，再删除。否则，删除一个id不存在的数据会抛出org.springframework.dao.EmptyResultDataAccessException异常：
2021-02-02 09:22:12.587 ERROR 13108 --- [ XNIO-1 task-2] c.a.s.b.e.GlobalExceptionHandler : No class com.atue.smarthome.manageplatform.domain.product.ProductType entity with id 2c9e8ce5774338d901775127a2420202 exists!
org.springframework.dao.EmptyResultDataAccessException: No class com.atue.smarthome.manageplatform.domain.product.ProductType entity with id 2c9e8ce5774338d901775127a2420202 exists!
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.lambda$deleteById$0(SimpleJpaRepository.java:157) ~[spring-data-jpa-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at java.util.Optional.orElseThrow(Optional.java:290) ~[na:1.8.0_181]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.deleteById(SimpleJpaRepository.java:156) ~[spring-data-jpa-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:359) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:644) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:295) ~[spring-tx-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:138) ~[spring-data-jpa-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.8.RELEASE.jar:2.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at com.sun.proxy.$Proxy163.deleteById(Unknown Source) ~[na:na]
在使用其他方法时，例如：deleteAllByName(name)，不进行判断也可以删除，不会抛出异常。