Actually, you can try the same error, install @hapi/iron, import it in a spec file, use the Iron.seal() with whatever data (e.g. the data from the screenshot) and you'll see the same error. I think the async await is an antipattern but that is not the focus, before that, I had the Iron.seal() inside a auth0 custom command sealing access token into a cookie, but that goes beyond this issue.