How do I add GraphQL error "extensions" in the Event Trigger response?

[kevinmichaelchen]

Current Approach

My current approach is just marshalling a struct to JSON, and then writing the JSON bytes as a response... Which yields something like this:

{
  "data": {
    "message": "{\"message\":\"failed to do a foo\",\"extensions\":{\"errors\":[{\"message\":\"API Error\"}]}}"
  },
  "type": "client_error",
  "version": "2"
}

It's Not Great

It would be nicer to see something like:

{
  "data": {
    "message": "failed to do a foo",
    "extensions": {
      "errors": [
        {
          "message": "API Error"
        }
      ]
    }
  },
  "type": "client_error",
  "version": "2"
}