Channel Manager logs NPE when the site is not running

When the site is not running and the CMS is accessed, the channel manager icon is not visible (see screenshot) and the following NPE is logged:

07.02.2012 09:06:29 ERROR [org.hippoecm.frontend.plugin.impl.PluginFactory.createPlugin():90] java.lang.NullPointerException: null
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.hippoecm.frontend.plugin.impl.PluginFactory.createPlugin(PluginFactory.java:72)
at org.hippoecm.frontend.plugin.impl.PluginManager.start(PluginManager.java:87)
at org.hippoecm.frontend.plugin.impl.PluginContext.start(PluginContext.java:320)
at org.hippoecm.frontend.plugin.impl.ClusterControl.start(ClusterControl.java:126)
at org.hippoecm.frontend.PluginPage.<init>(PluginPage.java:117)
at org.hippoecm.frontend.PluginPage.<init>(PluginPage.java:70)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.apache.wicket.session.DefaultPageFactory.createPage(DefaultPageFactory.java:192)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:57)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.newPage(BookmarkablePageRequestTarget.java:298)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.getPage(BookmarkablePageRequestTarget.java:320)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.processEvents(BookmarkablePageRequestTarget.java:234)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:92)
at org.hippoecm.frontend.PluginRequestCycleProcessor.processEvents(PluginRequestCycleProcessor.java:95)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1252)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1331)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1438)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:546)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:486)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:319)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.hippoecm.frontend.ResourceRewriteFilter.doFilter(ResourceRewriteFilter.java:129)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.hippoecm.frontend.plugins.login.ConcurrentLoginFilter.doFilter(ConcurrentLoginFilter.java:54)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:396)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at org.onehippo.cms7.channelmanager.channels.BlueprintStore.getBlueprints(BlueprintStore.java:93)
at org.onehippo.cms7.channelmanager.channels.BlueprintStore.getTotal(BlueprintStore.java:51)
at org.onehippo.cms7.channelmanager.channels.BlueprintStore.isEmpty(BlueprintStore.java:57)
at org.onehippo.cms7.channelmanager.RootPanel.<init>(RootPanel.java:100)
at org.onehippo.cms7.channelmanager.ChannelManagerPerspective.<init>(ChannelManagerPerspective.java:54)
... 47 more

Steps to reproduce:

1. start CMS and site locally:
mvn -P cargo.run

2. stop the site:
cd site
mvn cargo:undeploy

3. access http://localhost:8080/cms and login as admin

Expected behaviour: no warning is logged; the channel manager icon is shown, but no channels or blueprints are available
Actual behaviour: the warning described above is logged, and the channel manager icon is not visible