java.lang.AssertionError: Null textComponent
   at org.netbeans.modules.editor.lib2.view.ViewBuilder.repaintAndReplaceViews(ViewBuilder.java:340)
   at org.netbeans.modules.editor.lib2.view.ViewUpdates.checkRebuild(ViewUpdates.java:424)
   at org.netbeans.modules.editor.lib2.view.ViewUpdates$FactoriesListener.viewFactoryChanged(ViewUpdates.java:452)
   at org.netbeans.modules.editor.lib2.view.EditorViewFactory.fireEvent(EditorViewFactory.java:194)
   at org.netbeans.modules.editor.lib2.view.HighlightsViewFactory.highlightChanged(HighlightsViewFactory.java:226)
   at org.netbeans.spi.editor.highlighting.support.AbstractHighlightsContainer.fireHighlightsChange(AbstractHighlightsContainer.java:110)
   at org.netbeans.modules.editor.lib2.highlighting.CompoundHighlightsContainer.access$100(CompoundHighlightsContainer.java:64)
   at org.netbeans.modules.editor.lib2.highlighting.CompoundHighlightsContainer$2.run(CompoundHighlightsContainer.java:303)
   at org.netbeans.editor.BaseDocument.render(BaseDocument.java:1379)
   at org.netbeans.modules.editor.lib2.highlighting.CompoundHighlightsContainer.layerChanged(CompoundHighlightsContainer.java:301)
   at org.netbeans.modules.editor.lib2.highlighting.CompoundHighlightsContainer.access$400(CompoundHighlightsContainer.java:64)
   at org.netbeans.modules.editor.lib2.highlighting.CompoundHighlightsContainer$LayerListener.highlightChanged(CompoundHighlightsContainer.java:481)
   at org.netbeans.spi.editor.highlighting.support.AbstractHighlightsContainer.fireHighlightsChange(AbstractHighlightsContainer.java:110)
   at org.netbeans.modules.editor.lib2.highlighting.CaretBasedBlockHighlighting.updateLineInfo(CaretBasedBlockHighlighting.java:197)
   at org.netbeans.modules.editor.lib2.highlighting.CaretBasedBlockHighlighting.propertyChange(CaretBasedBlockHighlighting.java:157)
   at org.openide.util.WeakListenerImpl$PropertyChange.propertyChange(WeakListenerImpl.java:188)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:276)
   at java.awt.Component.firePropertyChange(Component.java:8213)
   at org.openide.text.QuietEditorPane.firePropertyChange(QuietEditorPane.java:204)
   at javax.swing.text.JTextComponent.setCaret(JTextComponent.java:585)
   at org.openide.text.QuietEditorPane.setCaret(QuietEditorPane.java:227)
   at org.netbeans.editor.BaseTextUI.uninstallUI(BaseTextUI.java:279)
   at javax.swing.JComponent.setUI(JComponent.java:639)
   at javax.swing.text.JTextComponent.setUI(JTextComponent.java:322)
   at javax.swing.text.JTextComponent.updateUI(JTextComponent.java:332)
   at org.netbeans.editor.BaseKit.deinstall(BaseKit.java:830)
   at javax.swing.JEditorPane.setEditorKit(JEditorPane.java:1091)
   at org.openide.text.CloneableEditor.componentClosed(CloneableEditor.java:820)
Caused: java.lang.IllegalStateException: [Winsys] TopComponent org.netbeans.modules.java.JavaDataObject$JavaEditor throws exception/error from its componentClosed() method.
Please repair it! Probable cause is at org.netbeans.modules.editor.lib2.view.ViewBuilder.repaintAndReplaceViews(ViewBuilder.java:340)
   at org.openide.windows.WindowManager.logThrowable(WindowManager.java:363)
   at org.openide.windows.WindowManager.componentCloseNotify(WindowManager.java:317)
   at org.netbeans.core.windows.WindowManagerImpl.notifyTopComponentClosed(WindowManagerImpl.java:979)
   at org.netbeans.core.windows.Central.removeModeTopComponent(Central.java:997)
   at org.netbeans.core.windows.Central.userClosedTopComponent(Central.java:1986)
   at org.netbeans.core.windows.view.DefaultView.userClosedTopComponent(DefaultView.java:741)
   at org.netbeans.core.windows.view.ui.TabbedHandler.actionPerformed(TabbedHandler.java:321)
   at org.netbeans.swing.tabcontrol.TabbedContainer.postActionEvent(TabbedContainer.java:692)
   at org.netbeans.swing.tabcontrol.TabbedContainerUI.shouldPerformAction(TabbedContainerUI.java:162)
   at org.netbeans.swing.tabcontrol.plaf.DefaultTabbedContainerUI.access$2700(DefaultTabbedContainerUI.java:109)
   at org.netbeans.swing.tabcontrol.plaf.DefaultTabbedContainerUI$DisplayerActionListener.actionPerformed(DefaultTabbedContainerUI.java:1266)
   at org.netbeans.swing.tabcontrol.TabDisplayer.postActionEvent(TabDisplayer.java:577)
   at org.netbeans.swing.tabcontrol.TabDisplayerUI.shouldPerformAction(TabDisplayerUI.java:185)
   at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI.access$1500(BasicTabDisplayerUI.java:117)
   at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.performCommand(BasicTabDisplayerUI.java:728)
   at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.potentialCommand(BasicTabDisplayerUI.java:713)
   at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.mouseReleased(BasicTabDisplayerUI.java:761)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272)
   at java.awt.Component.processMouseEvent(Component.java:6348)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3255)
   at java.awt.Component.processEvent(Component.java:6113)
   at java.awt.Container.processEvent(Container.java:2085)
   at java.awt.Component.dispatchEventImpl(Component.java:4714)
   at java.awt.Container.dispatchEventImpl(Container.java:2143)
   at java.awt.Component.dispatchEvent(Component.java:4544)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4618)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4282)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4212)
   at java.awt.Container.dispatchEventImpl(Container.java:2129)
   at java.awt.Window.dispatchEventImpl(Window.java:2475)
   at java.awt.Component.dispatchEvent(Component.java:4544)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:635)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:133)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)