Describe the feature

I tried ofetch with Bun. It seems to work, but I ran into a small issue when POSTing multipart/form-data. It seems the Bun FormData class has a toJSON method, while Node and Deno do not. It causes the isJSONSerializable() method to return true (exact line below), and therefore sends the serialized payload as application/json instead of multipart/form-data.

Would a value instanceof FormData check make sense here?

Additional information

• Would you be willing to help implement this feature?