NullPointerException in ElisionFilter on _analyze

[telendt]

Elasticsearch version (bin/elasticsearch --version):
Version: 7.1.1, Build: default/docker/7a013de/2019-05-23T14:04:00.380842Z, JVM: 12.0.1
(but happens in older versions too)

Steps to reproduce:

curl -sH 'Content-Type: application/json' 'localhost:9200/_analyze' -d '
{
  "text": "l’avion",
  "tokenizer": "standard",
  "filter": ["elision"]
}' | jq .

output:

{
  "error": {
    "root_cause": [
      {
        "type": "remote_transport_exception",
        "reason": "[12241dcbb809][172.20.0.2:9300][indices:admin/analyze[s]]"
      }
    ],
    "type": "null_pointer_exception",
    "reason": null
  },
  "status": 500
}

Provide logs (if relevant):

{
   "type":"server",
   "timestamp":"2019-06-07T19:15:38,854+0000",
   "level":"WARN",
   "component":"r.suppressed",
   "cluster.name":"docker-search-cluster",
   "node.name":"12241dcbb809",
   "cluster.uuid":"R-Zf6up6TXiv9aUhvgK03A",
   "node.id":"Fc9JysDfQm6Rp9FqaCu_Cg",
   "message":"path: /_analyze, params: {}",
   "stacktrace":[
      "org.elasticsearch.transport.RemoteTransportException: [12241dcbb809][172.20.0.2:9300][indices:admin/analyze[s]]",
      "Caused by: java.lang.NullPointerException",
      "at org.apache.lucene.analysis.util.ElisionFilter.incrementToken(ElisionFilter.java:66) ~[lucene-analyzers-common-8.0.0.jar:8.0.0 2ae4746365c1ee72a0047ced7610b2096e438979 - jimczi - 2019-03-08 11:59:47]",
      "at org.elasticsearch.action.admin.indices.analyze.TransportAnalyzeAction.simpleAnalyze(TransportAnalyzeAction.java:276) ~[elasticsearch-7.1.1.jar:7.1.1]",
      "at org.elasticsearch.action.admin.indices.analyze.TransportAnalyzeAction.analyze(TransportAnalyzeAction.java:251) ~[elasticsearch-7.1.1.jar:7.1.1]",
      "at org.elasticsearch.action.admin.indices.analyze.TransportAnalyzeAction.shardOperation(TransportAnalyzeAction.java:170) ~[elasticsearch-7.1.1.jar:7.1.1]",
      "at org.elasticsearch.action.admin.indices.analyze.TransportAnalyzeAction.shardOperation(TransportAnalyzeAction.java:81) ~[elasticsearch-7.1.1.jar:7.1.1]",
      "at org.elasticsearch.action.support.single.shard.TransportSingleShardAction$1.doRun(TransportSingleShardAction.java:117) [elasticsearch-7.1.1.jar:7.1.1]",
      "at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:751) [elasticsearch-7.1.1.jar:7.1.1]",
      "at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37) [elasticsearch-7.1.1.jar:7.1.1]",
      "at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]",
      "at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]",
      "at java.lang.Thread.run(Thread.java:835) [?:?]"
   ]
}

Few words of context:
Elision filter seems to work fine to me in regular analyzer (created at the index creation time), so it's probably something related to the way filters are used by analyze API.

[elasticmachine]

Pinging @elastic/es-search

[romseygeek]

Elision filter needs an 'articles' setting to work properly, which is missing from the analyze HTTP call you're making. It definitely shouldn't be producing an NPE though, it should give a more informative error at construction time.