java.lang.NullPointerException
        at javax.swing.plaf.basic.BasicTextUI$TextDropTargetListener.restoreComponentStateForDrop(BasicTextUI.java:2115)
        at javax.swing.plaf.basic.BasicDropTargetListener.drop(BasicDropTargetListener.java:259)
        at javax.swing.TransferHandler$SwingDropTarget.drop(TransferHandler.java:614)
        at org.openide.text.QuietEditorPane$DelegatingDropTarget.drop(QuietEditorPane.java:385)
        at sun.awt.dnd.SunDropTargetContextPeer.processDropMessage(SunDropTargetContextPeer.java:500)
        at sun.awt.dnd.SunDropTargetContextPeer.access$800(SunDropTargetContextPeer.java:53)
        at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchDropEvent(SunDropTargetContextPeer.java:812)
        at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchEvent(SunDropTargetContextPeer.java:736)
        at sun.awt.dnd.SunDropTargetEvent.dispatch(SunDropTargetEvent.java:29)
        at java.awt.Component.dispatchEventImpl(Component.java:3926)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4256)
        at java.awt.LightweightDispatcher.processDropTargetEvent(LightweightDispatcher.java:4007)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3861)
        at java.awt.Container.dispatchEventImpl(Container.java:2054)
        at java.awt.Window.dispatchEventImpl(Window.java:1791)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)