Hi Eric I catch the NPE in the NonAdjacentDocumentCollapser class and now it does return the data field collapsed.
However I can not promise how accurate or correct this fix is becuase I have not got allot of time to study all the code. It would be best if some of the experts could give us a clue I made the change in solr src java org apache solr search fieldcollapse NonAdjacentDocumentCollapser.java, inner class FloatValueFieldComparator.
