clicking twice on publish give NPE

java.lang.NullPointerException
at org.hippoecm.repository.reviewedactions.FullReviewedActionsWorkflowImpl.publish(FullReviewedActionsWorkflowImpl.java:50)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.hippoecm.repository.decorating.WorkflowManagerImpl$WorkflowInvocationHandler.invoke(WorkflowManagerImpl.java:435)
at $Proxy0.publish(Unknown Source)
at org.hippoecm.frontend.plugins.reviewedactions.FullReviewedActionsWorkflowPlugin$9.execute(FullReviewedActionsWorkflowPlugin.java:133)
at org.hippoecm.frontend.plugin.workflow.AbstractWorkflowPlugin$2.onClick(AbstractWorkflowPlugin.java:143)
at org.apache.wicket.ajax.markup.html.AjaxLink$1.onEvent(AjaxLink.java:65)
at org.apache.wicket.ajax.AjaxEventBehavior.respond(AjaxEventBehavior.java:163)
at org.apache.wicket.ajax.AbstractDefaultAjaxBehavior.onRequest(AbstractDefaultAjaxBehavior.java:293)
at org.apache.wicket.request.target.component.listener.BehaviorRequestTarget.processEvents(BehaviorRequestTarget.java:100)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:91)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1171)