Elasticsearch: Highlighting with nGrams (possible issue?)

gistfile1.js

curl -X PUT localhost:9200/myindex -d '
{
  "settings" : {
    "index":{
      "number_of_replicas":0,
      "number_of_shards":1,
      "analysis":{
        "analyzer":{
          "default":{
            "type":"custom",
            "tokenizer":"keyword",
            "filter":[
              "lowercase",
              "my_ngram"
            ]
          }
        },
        "filter":{
          "my_ngram":{
            "type":"nGram",
            "min_gram":1,
            "max_gram":20
          }
        }
      }
    }
  },
  "mappings" : {
    "product" : {
      "properties" : {
        "code" : {
          "type" : "multi_field",
          "fields" : {
            "code" : {
              "type" : "string",
              "analyzer" : "default",
              "store" : "yes"
            },
            "code.ngram" : {
              "type" : "string",
              "analyzer" : "default",
              "store" : "yes",
              "term_vector":"with_positions_offsets"
            }
          }
        }
      }
    }
  }
}'

# Now, index data

curl -X POST 'localhost:9200/myindex/product' -d '{
  "code" : "Samsung Galaxy i7500"
}'

curl -X POST 'localhost:9200/myindex/product' -d '{
  "code" : "Samsung Galaxy 5 Europa"
}'

curl -X POST 'localhost:9200/myindex/product' -d '{
  "code" : "Samsung Galaxy Mini"
}'

# ============================================
# After refresh, do some queries
# First, query just for a single character 'i'
# ============================================

curl -X GET 'localhost:9200/myindex/product/_search?pretty' -d '{
  "fields" : [ "code" ],
  "query" : {
    "term" : {
      "code" : "i"
    }
  },
  "highlight" : {
    "number_of_fragments" : 0,
    "fields" : {
      "code.ngram":{}
    }
  }
}'

# Works fine

... hit #1
      "fields" : {
        "code" : "Samsung Galaxy Mini"
      },
      "highlight" : {
        "code.ngram" : [ "Samsung Galaxy M<em>i</em>n<em>i</em>" ]
      }
... hit #2
      "fields" : {
        "code" : "Samsung Galaxy i7500"
      },
      "highlight" : {
        "code.ngram" : [ "Samsung Galaxy <em>i</em>7500" ]
      }

# Seems to works fine also for longer strings

curl -X GET 'localhost:9200/myindex/product/_search?pretty' -d '{
  "fields" : [ "code" ],
  "query" : {
    "term" : {
      "code" : "galaxy 5"
    }
  },
  "highlight" : {
    "number_of_fragments" : 0,
    "fields" : {
      "code.ngram":{}
    }
  }
}'

... hit #1
      "fields" : {
        "code" : "Samsung Galaxy 5 Europa"
      },
      "highlight" : {
        "code.ngram" : [ "Samsung <em>Galaxy 5</em> Europa" ]
      }
      
# ============================================
# Previous query would work only if user provide search terms in correct order.
# Now, let us try something fancy! Use query_string with whitespace analyzer.
# Search for 'mini sam'
# ============================================

curl -X GET 'localhost:9200/myindex/product/_search?pretty' -d '{
  "fields" : [ "code" ],
  "query" : {
    "query_string" : {
      "default_field" : "code.ngram",
      "query" : "mini sam",
      "analyzer" : "whitespace"
    }
  },
  "highlight" : {
    "number_of_fragments" : 0,
    "fields" : {
      "code.ngram":{}
    }
  }
}'
... hit #1
      "fields" : {
        "code" : "Samsung Galaxy Mini"
      },
      "highlight" : {
        "code.ngram" : [ "<em>Sam</em>sung Galaxy <em>Mini</em>" ]
      }
... hit #2
      "fields" : {
        "code" : "Samsung Galaxy i7500"
      },
      "highlight" : {
        "code.ngram" : [ "<em>Sam</em>sung Galaxy i7500" ]
      }
... hit #3
      "fields" : {
        "code" : "Samsung Galaxy 5 Europa"
      },
      "highlight" : {
        "code.ngram" : [ "<em>Sam</em>sung Galaxy 5 Europa" ]
      }
      
# Awesome!      
      
# ============================================
# But why query for 'sam xy' does not work? And why it fires an exception?
# ============================================

curl -X GET 'localhost:9200/myindex/product/_search?pretty' -d '{
  "fields" : [ "code" ],
  "query" : {
    "query_string" : {
      "default_field" : "code.ngram",
      "query" : "sam xy",
      "analyzer" : "whitespace"
    }
  },
  "highlight" : {
    "number_of_fragments" : 0,
    "fields" : {
      "code.ngram":{}
    }
  }
}'

# Response

{
  "error" : "SearchPhaseExecutionException[Failed to execute phase [query_fetch], total failure; shardFailures {[YsXZQqRWRP2rcyx6_eR_dQ][myindex][0]: FetchPhaseExecutionException[[myindex][0]: query[filtered(code.code.ngram:sam code.code.ngram:xy)->cache(_type:product)],from[0],size[10]: Fetch Failed [Failed to highlight field [code.ngram]]]; nested: StringIndexOutOfBoundsException[String index out of range: -14]; }]",
  "status" : 500
}

# Server log

2013-02-21 16:21:45,160][DEBUG][action.search.type       ] [Arachne] [myindex][0], node[YsXZQqRWRP2rcyx6_eR_dQ], [P], s[STARTED]: Failed to execute [org.elasticsearch.action.search.SearchRequest@7885a30c]
org.elasticsearch.search.fetch.FetchPhaseExecutionException: [myindex][0]: query[filtered(code.code.ngram:sam code.code.ngram:xy)->cache(_type:product)],from[0],size[10]: Fetch Failed [Failed to highlight field [code.ngram]]
  at org.elasticsearch.search.highlight.HighlightPhase.hitExecute(HighlightPhase.java:335)
	at org.elasticsearch.search.fetch.FetchPhase.execute(FetchPhase.java:250)
	at org.elasticsearch.search.SearchService.executeFetchPhase(SearchService.java:326)
	at org.elasticsearch.search.action.SearchServiceTransportAction.sendExecuteFetch(SearchServiceTransportAction.java:243)
	at org.elasticsearch.action.search.type.TransportSearchQueryAndFetchAction$AsyncAction.sendExecuteFirstPhase(TransportSearchQueryAndFetchAction.java:75)
	at org.elasticsearch.action.search.type.TransportSearchTypeAction$BaseAsyncAction.performFirstPhase(TransportSearchTypeAction.java:205)
	at org.elasticsearch.action.search.type.TransportSearchTypeAction$BaseAsyncAction.performFirstPhase(TransportSearchTypeAction.java:192)
	at org.elasticsearch.action.search.type.TransportSearchTypeAction$BaseAsyncAction$2.run(TransportSearchTypeAction.java:178)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
	at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -14
	at java.lang.String.substring(String.java:1937)
	at org.apache.lucene.search.vectorhighlight.BaseFragmentsBuilder.makeFragment(BaseFragmentsBuilder.java:166)
	at org.apache.lucene.search.vectorhighlight.AbstractFragmentsBuilder.createFragments(AbstractFragmentsBuilder.java:84)
	at org.apache.lucene.search.vectorhighlight.FastVectorHighlighter.getBestFragments(FastVectorHighlighter.java:186)
	at org.elasticsearch.search.highlight.HighlightPhase.hitExecute(HighlightPhase.java:327)
	... 10 more

I'm having this same problem. Did you ever figure out what the problem was?