While diagnosing how to make trapping signals work in Go, I identified that using an HTTP client has a bug. The call to processHTTPStatus here goes on to do proto.Unmarshal. When communicating with Honeycomb, this causes an error, because Honeycomb returns JSON.

Debug output:

guess we're almost done. resp:  &{200 OK 200 HTTP/1.1 1 1 map[Access-Control-Allow-Origin:[*] Connection:[keep-alive] Content-Length:[2] Content-Type:[application/json] Date:[Fri, 08 Sep 2023 02:16:22 GMT] Vary:[Accept-Encoding]] 0xc000674300 2 [] false false map[] 0xc00015e400 0xc000197a20}

Specifically Content-Type:[application/json].

Changing proto.Unmarshal to json.Unmarshal appears to fix the issue for the Honeycomb case, but i suspect that you'd want to use the content-type to determine the exact unmarshal function.