NullPointerException in ClientInstallationServiceImpl

javax.ejb.EJBException: java.lang.NullPointerException
      at org.jboss.as.ejb3.tx.CMTTxInterceptor.handleExceptionInOurTx(CMTTxInterceptor.java:190)
      at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:275)
      at org.jboss.as.ejb3.tx.CMTTxInterceptor.required(CMTTxInterceptor.java:340)
      at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:239)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.CurrentInvocationContextInterceptor.processInvocation(CurrentInvocationContextInterceptor.java:41)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.invocationmetrics.WaitTimeInterceptor.processInvocation(WaitTimeInterceptor.java:43)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.security.SecurityContextInterceptor.processInvocation(SecurityContextInterceptor.java:95)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.ShutDownInterceptorFactory$1.processInvocation(ShutDownInterceptorFactory.java:64)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.LoggingInterceptor.processInvocation(LoggingInterceptor.java:59)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.AdditionalSetupInterceptor.processInvocation(AdditionalSetupInterceptor.java:55)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.ContextClassLoaderInterceptor.processInvocation(ContextClassLoaderInterceptor.java:64)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:326)
      at org.wildfly.security.manager.WildFlySecurityManager.doChecked(WildFlySecurityManager.java:439)
      at org.jboss.invocation.AccessCheckingInterceptor.processInvocation(AccessCheckingInterceptor.java:61)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:326)
      at org.jboss.invocation.PrivilegedWithCombinerInterceptor.processInvocation(PrivilegedWithCombinerInterceptor.java:80)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
      at org.jboss.as.ee.component.ViewService$View.invoke(ViewService.java:185)
      at org.jboss.as.ee.component.ViewDescription$1.processInvocation(ViewDescription.java:182)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.LogDiagnosticContextRecoveryInterceptor.processInvocation(LogDiagnosticContextRecoveryInterceptor.java:79)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.AsyncFutureInterceptorFactory$1$2.runInvocation(AsyncFutureInterceptorFactory.java:97)
      at org.jboss.as.ejb3.component.interceptors.AsyncInvocationTask.run(AsyncInvocationTask.java:73)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)
      at org.jboss.threads.JBossThread.run(JBossThread.java:122)
Caused by: java.lang.NullPointerException
      at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.convertToNames(ClientInstallationServiceImpl.java:231)
      at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.mergeCategories(ClientInstallationServiceImpl.java:218)
      at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.updateInstallation(ClientInstallationServiceImpl.java:145)
      at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.addInstallation(ClientInstallationServiceImpl.java:79)
      at sun.reflect.GeneratedMethodAccessor478.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:497)
      at org.jboss.as.ee.component.ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptor.java:52)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53)
      at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:407)
      at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.doMethodInterception(Jsr299BindingsInterceptor.java:82)
      at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.processInvocation(Jsr299BindingsInterceptor.java:93)
      at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53)
      at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.invocationmetrics.ExecutionTimeInterceptor.processInvocation(ExecutionTimeInterceptor.java:43)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.jpa.interceptor.SBInvocationInterceptor.processInvocation(SBInvocationInterceptor.java:47)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:407)
      at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:55)
      at org.jboss.as.weld.ejb.EjbRequestScopeActivationInterceptor.processInvocation(EjbRequestScopeActivationInterceptor.java:83)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ee.concurrent.ConcurrentContextInterceptor.processInvocation(ConcurrentContextInterceptor.java:45)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
      at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:53)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.component.interceptors.NonPooledEJBComponentInstanceAssociatingInterceptor.processInvocation(NonPooledEJBComponentInstanceAssociatingInterceptor.java:59)
      at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
      at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:273)