let val = values
.next()
.ok_or(anyhow!("expected payload value, eg. '\"heartwood\"'"))?;
let val = json::from_str(val.to_string_lossy().to_string().as_str())?;
let val = val.to_string_lossy().to_string();
let val = json::from_str(val.as_str())
.map_err(|e| anyhow!("invalid JSON value `{val}`: {e}"))?;
payload.push((id, key, val));
}