java.lang.NullPointerException: Null child not allowed
    at javax.swing.tree.TreePath.pathByAddingChild(TreePath.java:327)
    at javax.swing.tree.VariableHeightLayoutCache$TreeStateNode.setParent(VariableHeightLayoutCache.java:1066)
    at javax.swing.tree.DefaultMutableTreeNode.insert(DefaultMutableTreeNode.java:187)
    at javax.swing.tree.DefaultMutableTreeNode.add(DefaultMutableTreeNode.java:411)
    at javax.swing.tree.VariableHeightLayoutCache$TreeStateNode.expand(VariableHeightLayoutCache.java:1486)
    at javax.swing.tree.VariableHeightLayoutCache$TreeStateNode.expand(VariableHeightLayoutCache.java:1288)
    at javax.swing.tree.VariableHeightLayoutCache.rebuild(VariableHeightLayoutCache.java:743)
    at javax.swing.tree.VariableHeightLayoutCache.setModel(VariableHeightLayoutCache.java:109)
    at javax.swing.plaf.basic.BasicTreeUI.setModel(BasicTreeUI.java:412)
    at javax.swing.plaf.basic.BasicTreeUI$Handler.propertyChange(BasicTreeUI.java:3414)
    at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327)
    at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:263)
    at java.awt.Component.firePropertyChange(Component.java:8430)
    at javax.swing.JTree.setModel(JTree.java:882)
    at fr.ifremer.isisfish.ui.script.ScriptUI.$completeSetup(ScriptUI.java:1362)
    at fr.ifremer.isisfish.ui.script.ScriptUI.$initialize(ScriptUI.java:1480)
    at fr.ifremer.isisfish.ui.script.ScriptUI. (ScriptUI.java:195)
    at fr.ifremer.isisfish.ui.WelcomeTabUI.$initialize(WelcomeTabUI.java:415)
    at fr.ifremer.isisfish.ui.WelcomeTabUI. (WelcomeTabUI.java:123)
    at fr.ifremer.isisfish.ui.WelcomeHandler.afterInit(WelcomeHandler.java:99)
    at fr.ifremer.isisfish.ui.WelcomeUI.$afterCompleteSetup(WelcomeUI.java:96)
    at fr.ifremer.isisfish.ui.WelcomeUI.$completeSetup(WelcomeUI.java:583)
    at fr.ifremer.isisfish.ui.WelcomeUI.$initialize(WelcomeUI.java:754)
    at fr.ifremer.isisfish.ui.WelcomeUI. (WelcomeUI.java:109)
    at fr.ifremer.isisfish.IsisFish$3.run(IsisFish.java:719)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)