java.lang.AssertionError
   at org.netbeans.spi.project.support.ant.SequentialPropertyEvaluator.stateChanged(SequentialPropertyEvaluator.java:160)
   at org.openide.util.WeakListenerImpl$Change.stateChanged(WeakListenerImpl.java:321)
   at org.openide.util.ChangeSupport.fireChange(ChangeSupport.java:130)
   at org.openide.util.ChangeSupport.fireChange(ChangeSupport.java:116)
   at org.netbeans.spi.project.support.ant.FilterPropertyProvider.setDelegate(FilterPropertyProvider.java:91)
   at org.netbeans.modules.javafx.project.JavaFXProject$ConfigPropertyProvider.run(JavaFXProject.java:238)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1369)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1907)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.AssertionError
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:368)
   at org.netbeans.modules.javafx.project.JavaFXProject$ConfigPropertyProvider.propertyChange(JavaFXProject.java:233)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
   at org.netbeans.spi.project.support.ant.SequentialPropertyEvaluator.stateChanged(SequentialPropertyEvaluator.java:205)
   at org.openide.util.WeakListenerImpl$Change.stateChanged(WeakListenerImpl.java:321)
   at org.openide.util.ChangeSupport.fireChange(ChangeSupport.java:130)
   at org.openide.util.ChangeSupport.fireChange(ChangeSupport.java:116)
   at org.netbeans.spi.project.support.ant.ProjectProperties$PP$2.run(ProjectProperties.java:345)
   at org.netbeans.spi.project.support.ant.ProjectProperties$PP$2.run(ProjectProperties.java:343)
   at org.openide.util.Mutex.readAccess(Mutex.java:285)
   at org.netbeans.spi.project.support.ant.ProjectProperties$PP.fireChange(ProjectProperties.java:351)
   at org.netbeans.spi.project.support.ant.ProjectProperties$PP.put(ProjectProperties.java:220)
   at org.netbeans.spi.project.support.ant.ProjectProperties.putProperties(ProjectProperties.java:128)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$6.run(AntProjectHelper.java:734)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$6.run(AntProjectHelper.java:732)
   at org.openide.util.Mutex.writeAccess(Mutex.java:394)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.putProperties(AntProjectHelper.java:732)
   at org.netbeans.modules.java.api.common.ant.UpdateHelper$2.run(UpdateHelper.java:114)
   at org.openide.util.Mutex.writeAccess(Mutex.java:469)
   at org.netbeans.modules.java.api.common.ant.UpdateHelper.putProperties(UpdateHelper.java:109)
   at org.netbeans.modules.javafx.project.JavaFXConfigurationProvider.setActiveConfiguration(JavaFXConfigurationProvider.java:256)
   at org.netbeans.modules.javafx.project.JavaFXConfigurationProvider.setActiveConfiguration(JavaFXConfigurationProvider.java:81)
   at org.netbeans.modules.project.ui.actions.ActiveConfigAction$10.run(ActiveConfigAction.java:516)
   at org.netbeans.modules.project.ui.actions.ActiveConfigAction$10.run(ActiveConfigAction.java:514)
   at org.openide.util.Mutex.writeAccess(Mutex.java:433)
   at org.netbeans.modules.project.ui.actions.ActiveConfigAction.setActiveConfiguration(ActiveConfigAction.java:514)
   at org.netbeans.modules.project.ui.actions.ActiveConfigAction.activeConfigurationSelected(ActiveConfigAction.java:238)
   at org.netbeans.modules.project.ui.actions.ActiveConfigAction.access$600(ActiveConfigAction.java:93)
   at org.netbeans.modules.project.ui.actions.ActiveConfigAction$2.actionPerformed(ActiveConfigAction.java:148)
   at javax.swing.JComboBox.fireActionEvent(JComboBox.java:1240)
   at javax.swing.JComboBox.setSelectedItem(JComboBox.java:567)
   at javax.swing.JComboBox.setSelectedIndex(JComboBox.java:603)
   at javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(BasicComboPopup.java:816)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:273)
   at java.awt.Component.processMouseEvent(Component.java:6263)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
   at javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(BasicComboPopup.java:480)
   at java.awt.Component.processEvent(Component.java:6028)
   at java.awt.Container.processEvent(Container.java:2041)
   at java.awt.Component.dispatchEventImpl(Component.java:4630)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4574)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4238)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4168)
   at java.awt.Container.dispatchEventImpl(Container.java:2085)
   at java.awt.Window.dispatchEventImpl(Window.java:2475)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:133)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)