Confusing error message when trying to add second mapping type

[cbuescher]

I just came across this slightly confusing error message when playing around with things for #31906.

When creating an index with type "type1", then trying to add a second type "type" two gives the following error:

PUT test
{
    "mappings" : {
        "type1" : {
        }
    }
}

PUT twitter/_mapping/type2 
{
  "properties": {
    "email": {
      "type": "keyword"
    }
  }
}

-> "Rejecting mapping update to [twitter] as the final mapping would have more than 1 type: [type2, _doc]"

I would have expected "[type2, type1]" or something like that instead since I haven't used the "_doc" type anywhere. Tried this on 6.2.4, will see how it looks like in newer versions.

[elasticmachine]

Pinging @elastic/es-search-aggs

[cbuescher]

Nevermind, saw the error. D'oh, facepalm!