Add assertion error

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
 at com.eviware.soapui.impl.wsdl.panels.assertions.AddAssertionPanel$CategoryListRenderer.getTableCellRendererComponent(AddAssertionPanel.java:531)
 at javax.swing.JTable$AccessibleJTable.getAccessibleChild(Unknown Source)
 at javax.swing.JTable$AccessibleJTable.getAccessibleAt(Unknown Source)
 at javax.swing.JTable$AccessibleJTable.valueChanged(Unknown Source)
 at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
 at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
 at javax.swing.DefaultListSelectionModel.setValueIsAdjusting(Unknown Source)
 at javax.swing.plaf.basic.BasicTableUI$Handler.setValueIsAdjusting(Unknown Source)
 at javax.swing.plaf.basic.BasicTableUI$Handler.mouseReleased(Unknown Source)
 at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
 at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
 at java.awt.Component.processMouseEvent(Unknown Source)
 at javax.swing.JComponent.processMouseEvent(Unknown Source)
 at java.awt.Component.processEvent(Unknown Source)
 at java.awt.Container.processEvent(Unknown Source)
 at java.awt.Component.dispatchEventImpl(Unknown Source)
 at java.awt.Container.dispatchEventImpl(Unknown Source)
 at java.awt.Component.dispatchEvent(Unknown Source)
 at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
 at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
 at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
 at java.awt.Container.dispatchEventImpl(Unknown Source)
 at java.awt.Window.dispatchEventImpl(Unknown Source)
 at java.awt.Component.dispatchEvent(Unknown Source)
 at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
 at java.awt.EventQueue.access$200(Unknown Source)
 at java.awt.EventQueue$3.run(Unknown Source)
 at java.awt.EventQueue$3.run(Unknown Source)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
 at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
 at java.awt.EventQueue$4.run(Unknown Source)
 at java.awt.EventQueue$4.run(Unknown Source)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
 at java.awt.EventQueue.dispatchEvent(Unknown Source)
 at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
 at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
 at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
 at java.awt.WaitDispatchSupport$2.run(Unknown Source)
 at java.awt.WaitDispatchSupport$4.run(Unknown Source)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.awt.WaitDispatchSupport.enter(Unknown Source)
 at java.awt.Dialog.show(Unknown Source)
 at java.awt.Component.show(Unknown Source)
 at java.awt.Component.setVisible(Unknown Source)
 at java.awt.Window.setVisible(Unknown Source)
 at java.awt.Dialog.setVisible(Unknown Source)
 at com.eviware.soapui.impl.wsdl.actions.project.SimpleDialog.setVisible(SimpleDialog.java:124)
 at com.eviware.soapui.impl.wsdl.teststeps.actions.AddAssertionAction$1.run(AddAssertionAction.java:61)
 at java.awt.event.InvocationEvent.dispatch(Unknown Source)
 at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
 at java.awt.EventQueue.access$200(Unknown Source)
 at java.awt.EventQueue$3.run(Unknown Source)
 at java.awt.EventQueue$3.run(Unknown Source)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
 at java.awt.EventQueue.dispatchEvent(Unknown Source)
 at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
 at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
 at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
 at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
 at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
 at java.awt.EventDispatchThread.run(Unknown Source)