NullPointerException during server startup, when called by monitoring tool

01:08:28,058 ERROR [org.jboss.as.controller.management-operation] (pool-1-thread-5) WFLYCTL0013: operation ("read-attribute") failed - address: ([
    ("deployment" => "app.war"),
    ("subsystem" => "undertow")
]): java.lang.NullPointerException
        at org.wildfly.extension.undertow.DeploymentDefinition$SessionManagerStatsHandler.executeRuntimeStep(DeploymentDefinition.java:304)
        at org.jboss.as.controller.AbstractRuntimeOnlyHandler$1.execute(AbstractRuntimeOnlyHandler.java:59)
        at org.jboss.as.controller.AbstractOperationContext.executeStep(AbstractOperationContext.java:999)
        at org.jboss.as.controller.AbstractOperationContext.processStages(AbstractOperationContext.java:743)
        at org.jboss.as.controller.AbstractOperationContext.executeOperation(AbstractOperationContext.java:467)
        at org.jboss.as.controller.OperationContextImpl.executeOperation(OperationContextImpl.java:1413)
        at org.jboss.as.controller.ModelControllerImpl.internalExecute(ModelControllerImpl.java:429)
        at org.jboss.as.controller.ModelControllerImpl.lambda$execute$0(ModelControllerImpl.java:230)
        at org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:289)
        at org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:255)
        at org.jboss.as.controller.ModelControllerImpl.execute(ModelControllerImpl.java:230)
        at org.jboss.as.jmx.model.ModelControllerMBeanHelper.execute(ModelControllerMBeanHelper.java:570)
        at org.jboss.as.jmx.model.ModelControllerMBeanHelper.getAttribute(ModelControllerMBeanHelper.java:316)
        at org.jboss.as.jmx.model.ModelControllerMBeanHelper.getAttributes(ModelControllerMBeanHelper.java:294)
        at org.jboss.as.jmx.model.ModelControllerMBeanServerPlugin.getAttributes(ModelControllerMBeanServerPlugin.java:148)
        at org.jboss.as.jmx.PluggableMBeanServerImpl.getAttributes(PluggableMBeanServerImpl.java:419)
        at io.prometheus.jmx.shaded.io.prometheus.jmx.JmxScraper.scrapeBean(JmxScraper.java:151)
        at io.prometheus.jmx.shaded.io.prometheus.jmx.JmxScraper.doScrape(JmxScraper.java:117)
        at io.prometheus.jmx.shaded.io.prometheus.jmx.JmxCollector.collect(JmxCollector.java:456)
        at io.prometheus.jmx.shaded.io.prometheus.client.CollectorRegistry$MetricFamilySamplesEnumeration.findNextElement(CollectorRegistry.java:183)
        at io.prometheus.jmx.shaded.io.prometheus.client.CollectorRegistry$MetricFamilySamplesEnumeration.nextElement(CollectorRegistry.java:216)
        at io.prometheus.jmx.shaded.io.prometheus.client.CollectorRegistry$MetricFamilySamplesEnumeration.nextElement(CollectorRegistry.java:137)
        at io.prometheus.jmx.shaded.io.prometheus.client.exporter.common.TextFormat.write004(TextFormat.java:22)
        at io.prometheus.jmx.shaded.io.prometheus.client.exporter.HTTPServer$HTTPMetricHandler.handle(HTTPServer.java:59)
        at com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:79)
        at sun.net.httpserver.AuthFilter.doFilter(AuthFilter.java:83)
        at com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:82)
        at sun.net.httpserver.ServerImpl$Exchange$LinkHandler.handle(ServerImpl.java:675)
        at com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:79)
        at sun.net.httpserver.ServerImpl$Exchange.run(ServerImpl.java:647)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)