Странная ошибка в приложении Swing

Делаю редактор кода с подсветкой синтаксиса на Swing в NetBeans 8.2. Использую тему Motif.
Через раз при запуске выходит странная ошибка:

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: javax.swing.JPanel[,0,0,0x0,invalid,layout=javax.swing.GroupLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=9,maximumSize=,minimumSize=,preferredSize=] is not attached to a horizontal group
at javax.swing.GroupLayout.checkComponents(GroupLayout.java:1086)
at javax.swing.GroupLayout.prepare(GroupLayout.java:1040)
at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:910)
at java.awt.Container.layout(Container.java:1510)
at java.awt.Container.doLayout(Container.java:1499)
at java.awt.Container.validateTree(Container.java:1695)
at java.awt.Container.validateTree(Container.java:1704)
at java.awt.Container.validateTree(Container.java:1704)
at java.awt.Container.validate(Container.java:1630)
at javax.swing.RepaintManager$3.run(RepaintManager.java:711)
at javax.swing.RepaintManager$3.run(RepaintManager.java:709)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:708)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1731)
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:80)
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)  

Самое необычное что нет даже упоминания на мою программу - ни знакомого имени класса, ни ссылки на мной написанную строку.