NPE when stopping publisher bundle

[kaikreuzer]

I just had this in my log file:

Caused by: java.lang.NullPointerException
        at com.eclipsesource.jaxrs.publisher.internal.ServiceContainer$Finder.findServiceHolder(ServiceContainer.java:113)
        at com.eclipsesource.jaxrs.publisher.internal.ServiceContainer.find(ServiceContainer.java:52)
        at com.eclipsesource.jaxrs.publisher.internal.JAXRSConnector.cacheFreedResources(JAXRSConnector.java:153)
        at com.eclipsesource.jaxrs.publisher.internal.JAXRSConnector.doRemoveHttpService(JAXRSConnector.java:145)
        at com.eclipsesource.jaxrs.publisher.internal.JAXRSConnector.removeHttpService(JAXRSConnector.java:138)
        at com.eclipsesource.jaxrs.publisher.internal.HttpTracker.removedService(HttpTracker.java:38)
        at org.osgi.util.tracker.ServiceTracker$Tracked.customizerRemoved(ServiceTracker.java:967)[org.osgi.core-6.0.0.jar:]
        at org.osgi.util.tracker.ServiceTracker$Tracked.customizerRemoved(ServiceTracker.java:870)[org.osgi.core-6.0.0.jar:]
        at org.osgi.util.tracker.AbstractTracked.untrack(AbstractTracked.java:341)[org.osgi.core-6.0.0.jar:]
        at org.osgi.util.tracker.ServiceTracker.close(ServiceTracker.java:377)[org.osgi.core-6.0.0.jar:]
        at com.eclipsesource.jaxrs.publisher.internal.Activator.stop(Activator.java:104)

Used version is 5.3.1.