Invalid Facet Query NPE Test Case

gistfile1.bash

#!/bin/bash

curl -S -XDELETE http://localhost:9200/testindex > /dev/null
curl -S -XPUT http://localhost:9200/testindex > /dev/null
curl -XPOST http://localhost:9200/testindex/_search?pretty=true -d '{
    "query" : { "match_all" : {} },
    "facets" : {
        "tags" : {
            "field" : "tag",
            "size" : 3
        }
    }
}'