on this line, the typeof request.body === 'object' check returns true for FormData from undici and form-data. Resulting in a body of "{}" being sent, with content-type: application/json; charset=utf-8

I think there's a few potential solutions here:

• Check the content-type, and if it's set, do not attempt to coerce to JSON.
• Check the json property in Request to be exactly false. This property doesn't appear to be used?
• Check instanceof FormData from undici, I don't think this is a great option but it's an option.