NPE for BlockJoinFacetComponent and facet.prefix not working

14:00:20,751 ERROR [org.apache.solr.servlet.HttpSolrCall] (http-/10.235.43.43:8580-82) null:java.lang.NullPointerException
        at org.apache.solr.search.join.BlockJoinFacetCollector.incrementFacets(BlockJoinFacetCollector.java:100)
        at org.apache.solr.search.join.BlockJoinFacetCollector.collect(BlockJoinFacetCollector.java:87)

15:07:56,736 INFO  [org.apache.solr.core.SolrCore.Request] (http-/10.235.43.43:8580-143) [core1]  webapp=/solr path=/select 
params={shards.qt=searchStandard&tie=0.01&stats=true&distrib=false&q.alt=*:*&originIP=10.235.52.131&collection=search1&shards.tolerant=true&version=2&NOW=1454360876733&shard.url=http://solrx331p.qa.ch3.s.com:8580/solr/core1/|http://solrx351p.qa.ch3.s.com:8580/solr/core1/&fl=id&fl=score&bf=%0a++++++++++++&timeAllowed=10000&qt=searchStandard&fsv=true&fq=catalogs:(("10104"))&fq=searchableAttributes:(("Metal%3DTri+color"))&fq=brand:("Black+Hills+Gold")&fq=discount:("70")&fq=primaryCategory:("10104_3_Jewelry_Diamonds_Rings")&mm=%0a++++++++++++++++2<-1+5<-2+6<-50%25%0a++++++++++++&hasOrigCategories=1&qf=%0a+++++++++++++++++primaryLnames^5.0+partnumber^11.0+itemnumber^11.0+fullmfpartno^5.0+mfpartno^5.0+xref^10.0+storeOriginSearchable^3.0+nameSearchable^10.0+brandSearchable^5.0++searchPhrase^1.0++searchableAttributesSearchable^1.0++++%0a++++++++++++&wt=javabin&rows=0&pf=%0a+++++++++++++++primaryLnames^0.5+nameSearchable^1.0+storeOriginSearchable^0.3+brandSearchable^0.5++xref^1.1+searchableAttributesSearchable^0.1%0a++++++++++++&shards.purpose=516&start=0&q=white+diamonds+diamonds+elizabeth+taylor+body+lotion&bot=true&stats.field=price_10151_f&isShard=true&ps=100} hits=0 status=0 QTime=0


15:07:56,758 ERROR [org.apache.solr.handler.RequestHandlerBase] (http-/10.235.43.43:8580-26) java.lang.NullPointerException
        at org.apache.solr.search.join.BlockJoinFacetCollector.incrementFacets(BlockJoinFacetCollector.java:100)
        at org.apache.solr.search.join.BlockJoinFacetCollector.collect(BlockJoinFacetCollector.java:87)
        at org.apache.solr.search.SolrIndexSearcher.getDocSet(SolrIndexSearcher.java:1153)
        at org.apache.solr.handler.component.QueryComponent.process(QueryComponent.java:350)
        at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:273)
        at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:156)