Throwing erros in cloud functions and showing them in FlutterFlow

I am throwing an error in cloud functions like this:

throw new HttpsError("internal", error);

This is the response in the browser:

{
    "error": {
        "message": "AxiosError: Request failed with status code 400",
        "status": "INTERNAL"
    }
}

I want to show that message in a snackbar, how is this accomplished
I tried with $["error"]["message"]
This shows the snackbar with the word null in it