NPE error while undeploying

[Wally Hartshorn]

I just undeployed a webapp I am developing and saw this error in the catalina.log file:

Mar 26, 2008 9:25:28 AM org.apache.catalina.startup.HostConfig checkResources
INFO: Undeploying context [/myapp]
Mar 26, 2008 9:25:29 AM org.apache.catalina.startup.HostConfig checkResources
INFO: Undeploying context [/myapp]
Mar 26, 2008 9:25:29 AM org.apache.catalina.startup.HostConfig checkResources
WARNING: Error while removing context [/myapp]
java.lang.NullPointerException
at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:884)
at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1046)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1214)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:293)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:120)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1306)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1570)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1579)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1559)
at java.lang.Thread.run(Unknown Source)
Mar 26, 2008 9:25:29 AM org.apache.catalina.startup.HostConfig checkResources
WARNING: Error during context [/myapp] destroy
java.lang.NullPointerException
at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1052)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1214)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:293)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:120)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1306)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1570)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1579)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1559)
at java.lang.Thread.run(Unknown Source)

The webapp appears to have been undeployed successfully, but I'm a bit worried about this error message. I've been having some symptoms that I suspect might indicate a memory leak or some failure to free a resource, and I'm wondering whether this error message might be related.

Does anyone have any ideas about what this might mean and/or how to investigate it further?

This happened while running Tomcat 5.5.26, JVM 1.5.0_15, and Windows XP.