Registry throws NPE when deleting schema metadata with no schema versions

[raju-saravanan]

Encountered following error while deleting a schema metadata,

ERROR [2020-01-22 07:01:34,205] com.hortonworks.registries.schemaregistry.webservice.SchemaRegistryResource: Encountered error while deleting schema with name: [schema2]
! java.lang.NullPointerException: null
! at com.hortonworks.registries.schemaregistry.DefaultSchemaRegistry.getSchemaSerDesMappings(DefaultSchemaRegistry.java:883)
! at com.hortonworks.registries.schemaregistry.DefaultSchemaRegistry.deleteSchema(DefaultSchemaRegistry.java:311)
! at com.hortonworks.registries.schemaregistry.webservice.SchemaRegistryResource.deleteSchemaMetadata(SchemaRegistryResource.java:499)
! at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
! at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
! at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
! at java.lang.reflect.Method.invoke(Method.java:498)
! at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
! at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
! at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
! at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:160)
! at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
! at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
! at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
! at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
! at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
! at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
! at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
! at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
! at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
! at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
! at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
! at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
! at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
! at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
! at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
! at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
! at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
! at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
! at io.dropwizard.jetty.NonblockingServletHolder.handle(NonblockingServletHolder.java:49)
! at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1655)
! at io.dropwizard.servlets.ThreadNameFilter.doFilter(ThreadNameFilter.java:34)
! at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
! at io.dropwizard.jersey.filter.AllowedMethodsFilter.handle(AllowedMethodsFilter.java:45)
! at io.dropwizard.jersey.filter.AllowedMethodsFilter.doFilter(AllowedMethodsFilter.java:39)
! at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
! at com.hortonworks.registries.schemaregistry.webservice.RewriteUriFilter.doFilter(RewriteUriFilter.java:77)
! at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
! at org.eclipse.jetty.servlets.CrossOriginFilter.handle(CrossOriginFilter.java:311)
! at org.eclipse.jetty.servlets.CrossOriginFilter.doFilter(CrossOriginFilter.java:265)
! at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
! at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
! at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255)
! at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1317)
! at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203)
! at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
! at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201)
! at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1219)
! at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144)
! at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
! at com.codahale.metrics.jetty9.InstrumentedHandler.handle(InstrumentedHandler.java:241)
! at io.dropwizard.jetty.RoutingHandler.handle(RoutingHandler.java:52)
! at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:674)
! at io.dropwizard.jetty.BiDiGzipHandler.handle(BiDiGzipHandler.java:69)
! at org.eclipse.jetty.server.handler.RequestLogHandler.handle(RequestLogHandler.java:56)
! at org.eclipse.jetty.server.handler.StatisticsHandler.handle(StatisticsHandler.java:169)
! at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
! at org.eclipse.jetty.server.Server.handle(Server.java:531)
! at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:352)
! at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:260)
! at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:281)
! at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:102)
! at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:118)
! at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:333)
! at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:310)
! at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:168)
! at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:126)
! at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:366)
! at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:762)
! at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:680)
! at java.lang.Thread.run(Thread.java:745)
0:0:0:0:0:0:0:1 - - [22/Jan/2020:07:01:34 +0000] "DELETE /api/v1/schemaregistry/schemas/schema2 HTTP/1.1" 500 111 "http://localhost:9090/swagger" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.75 Safari/537.36" 8