java.lang.IllegalArgumentException: Called DataObject.find on null
   at org.openide.loaders.DataObject.find(DataObject.java:551)
   at org.netbeans.modules.html.custom.conf.Configuration.store(Configuration.java:295)
   at org.netbeans.modules.html.custom.hints.AddElementFix.implement(AddElementFix.java:79)
   at org.netbeans.modules.csl.hints.infrastructure.FixWrapper.implement(FixWrapper.java:66)
   at org.netbeans.modules.editor.hints.HintsUI$1.run(HintsUI.java:837)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1432)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2042)