Object mapping [categories] can't be changed from nested to non-nested

Elastic Stack Elasticsearch
6

I can not just copy and paste your script to run it in Kibana dev console. As we wrote in the About the Elasticsearch category guide, could you provide something like:

DELETE index
PUT index/_doc/1
{
  "foo": "bar"
}
GET index/_search
{
  "query": {
    "match": {
      "foo": "bar"
    }
  }
}