java.lang.AssertionError: Should be a folder: C:\Users\Mark\Documents\NetBeansProjects\Check-MasterDetailProject\build\classes\javaapplication5@6eb313b9:194b4f7
   at org.netbeans.modules.masterfs.watcher.Watcher$Ext.unregister(Watcher.java:253)
   at org.netbeans.modules.masterfs.watcher.Watcher.unregister(Watcher.java:134)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.BaseFileObj.removeFileChangeListener(BaseFileObj.java:508)
   at org.openide.filesystems.FileUtil$Holder.run(FileUtil.java:554)
   at org.openide.util.lookup.implspi.ActiveQueue$Impl.run(ActiveQueue.java:109)
   at java.lang.Thread.run(Thread.java:722)