java.util.ConcurrentModificationException
   at java.util.WeakHashMap$HashIterator.nextEntry(WeakHashMap.java:882)
   at java.util.WeakHashMap$EntryIterator.next(WeakHashMap.java:921)
   at java.util.WeakHashMap$EntryIterator.next(WeakHashMap.java:919)
   at org.openide.text.DocumentOpenClose.updateLines(DocumentOpenClose.java:506)
   at org.openide.text.DocumentOpenClose$DocumentLoad.run(DocumentOpenClose.java:678)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)