Kibana version: master

Elasticsearch version: master

Server OS version: Linux 4.7.2-1

Browser version: Chrome Version 53.0.2785.89 (64-bit)

Browser OS version: Linux 4.7.2-1

Original install method (e.g. download page, yum, from source, etc.): from source

Description of the problem including expected versus actual behavior:

Clicking the + loop filter for value when the field's value is NULL throws an error:

Steps to reproduce:

1. Add data

   $ curl -XPOST 'localhost:9200/city/City' -d '
   {
   "bornIn": null,
   "person": "john"
   }
   '
   $ curl -XPOST 'localhost:9200/city/City' -d '
   {
   "bornIn": "past",
   "person": "connor"
   }
   '

2. click on the Filter for value lense icon for the first document (value of bornIn is null)

3. you get the error unknown token [VALUE_NULL] after [query]