java.lang.NullPointerException
        at org.openide.filesystems.Repository.removeFileSystem(Repository.java:193)
[catch] at org.netbeans.modules.web.context.WebContextObject$FSRemover.run(WebContextObject.java:539)
        at org.openide.util.Task.run(Task.java:136)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:330)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:670)