java.lang.NullPointerException
   at org.netbeans.editor.Annotations.addAnnotation(Annotations.java:224)
   at org.netbeans.modules.editor.NbEditorDocument.addAnnotation(NbEditorDocument.java:244)
   at org.openide.text.NbDocument.addAnnotation(NbDocument.java:518)
   at org.openide.text.DocumentLine$Part$1.run(DocumentLine.java:744)
   at org.netbeans.editor.BaseDocument.render(BaseDocument.java:1391)
   at org.openide.text.DocumentLine$Part.addAnnotation(DocumentLine.java:738)
   at org.openide.text.Annotation.attach(Annotation.java:120)
   at org.netbeans.modules.editor.NbToolTip$Request.resolveTooltipText(NbToolTip.java:403)
   at org.netbeans.modules.editor.NbToolTip$Request.run(NbToolTip.java:365)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)