Error on reveal alternative vote

[1-alex98]

2019-05-07 23:01:56.356 ERROR 1 --- [085c7009-c886-4d81-b762-ba8c7c11dd80] [p251520863-8747] com.yahoo.elide.Elide                    : Error or exception uncaught by Elide

java.lang.NullPointerException: null
	at com.faforever.api.data.listeners.VotingSubjectEnricher.lambda$null$6(VotingSubjectEnricher.java:112)
	at java.util.Optional.ifPresent(Optional.java:159)
	at com.faforever.api.data.listeners.VotingSubjectEnricher.lambda$null$7(VotingSubjectEnricher.java:110)
	at java.util.ArrayList.forEach(ArrayList.java:1257)
	at com.faforever.api.data.listeners.VotingSubjectEnricher.lambda$getWinners$8(VotingSubjectEnricher.java:105)
	at java.util.ArrayList.forEach(ArrayList.java:1257)
	at com.faforever.api.data.listeners.VotingSubjectEnricher.getWinners(VotingSubjectEnricher.java:101)
	at com.faforever.api.data.listeners.VotingSubjectEnricher.calculateWinners(VotingSubjectEnricher.java:63)
	at java.lang.Iterable.forEach(Iterable.java:75)
	at com.faforever.api.data.listeners.VotingSubjectEnricher.updateWinners(VotingSubjectEnricher.java:44)
	at com.faforever.api.data.listeners.VotingSubjectEnricher.preUpdate(VotingSubjectEnricher.java:40)
	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.hibernate.jpa.event.internal.jpa.ListenerCallback.performCallback(ListenerCallback.java:35)
	at org.hibernate.jpa.event.internal.jpa.CallbackRegistryImpl.callback(CallbackRegistryImpl.java:97)
	at org.hibernate.jpa.event.internal.jpa.CallbackRegistryImpl.preUpdate(CallbackRegistryImpl.java:71)
	at org.hibernate.jpa.event.internal.core.JpaFlushEntityEventListener.invokeInterceptor(JpaFlushEntityEventListener.java:51)
	at org.hibernate.event.internal.DefaultFlushEntityEventListener.handleInterception(DefaultFlushEntityEventListener.java:321)
	at org.hibernate.event.internal.DefaultFlushEntityEventListener.scheduleUpdate(DefaultFlushEntityEventListener.java:272)
	at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:143)
	at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:216)
	at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:85)
	at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:38)
	at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1437)
	at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1423)
	at com.yahoo.elide.datastores.hibernate5.HibernateTransaction.flush(HibernateTransaction.java:90)
	at com.yahoo.elide.Elide.handleRequest(Elide.java:216)
	at com.yahoo.elide.Elide.patch(Elide.java:164)
	at com.faforever.api.data.DataController.patch(DataController.java:92)
	at com.faforever.api.data.DataController$$FastClassBySpringCGLIB$$793f0f27.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:69)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
	at com.faforever.api.data.DataController$$EnhancerBySpringCGLIB$$85580c55.patch(<generated>)
	at sun.reflect.GeneratedMethodAccessor1334.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:891)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:848)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:865)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1655)
	at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:215)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
	at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.oauth2.provider.authentication.OAuth2AuthenticationProcessingFilter.doFilter(OAuth2AuthenticationProcessingFilter.java:176)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:66)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
	at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:357)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:270)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:155)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:123)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:108)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
	at com.faforever.api.logging.RequestIdFilter.doFilter(RequestIdFilter.java:61)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:146)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:257)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1340)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1242)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
	at org.eclipse.jetty.server.Server.handle(Server.java:503)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:364)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:260)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:305)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
	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:765)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:683)
	at java.lang.Thread.run(Thread.java:748)
	Suppressed: java.io.IOException: Transaction not closed
		at com.faforever.api.config.elide.SpringHibernateTransaction.close(SpringHibernateTransaction.java:74)
		at com.yahoo.elide.Elide.handleRequest(Elide.java:231)
		... 101 common frames omitted

Gorton ran an alternative vote and this error happened.
I was able to reproduce the exact same error in a unit test and fixed the issue. It happens in really rare cases.

So this bug appears if 2 candidates have the same amount of votes and get eliminated at once and if then after the first one is eliminated and his votes are distributed to the remaining, the second one has a vote that goes to the first one afterwards. Because the 1st one was eliminated it is no longer existing the program tries to associate the vote with the eliminated candidate and crashed....