This comes from a discussion with @jpountz after looking at #31476.
Range and wildcard queries throw an error when run against a _type field for single-type indices in 6.x and most likely also
in master. While _type is deprecated, it might still we worth fixing these for the time being. In the other hand it seems to be a
rare use-case to query the _type field with a range query, so I'd probably discuss this before diving deeper into it.