Output valid TileJSON for PostgreSQL Function Sources

[ohrie]

When using the (simple function) example from martin docs for PostgreSQL Function Sources, the resulting TileJSON looks like this:

{
  "tilejson": "3.0.0",
  "tiles": [
    "https://<YOURTILESERVER>.com/function_zxy_query/{z}/{x}/{y}"
  ],
  "description": "public.function_zxy_query",
  "name": "function_zxy_query"
}

This is not a valid TileJSON, because the TileJSON spec requires the fields attribute to be present. Therefore the usage in MapLibre fails.

I currently don't know how to implement an according solution. The solution modyfing the TileJSON via the COMMENT SQL statement further down the docs didn't work.