java.lang.NullPointerException: This exception has no message.

java.lang.NullPointerException: 	at com.kuba.crud.resources.CustomerResource.getCustomers(CustomerResource.java:37)	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$1.run(AbstractJavaResourceMethodDispatcher.java:144)	at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)	at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205)	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 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)	at org.apache.tomee.webservices.CXFJAXRSFilter.doFilter(CXFJAXRSFilter.java:83)	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)	at org.apache.openejb.server.httpd.EEFilter.doFilter(EEFilter.java:65)	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)	at org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:44)	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:522)	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1110)	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:785)	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1425)	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)	at java.lang.Thread.run(Thread.java:745)