* Fix bug with "Circular Structure" error
Since `-1` is truthy, every JSON.stringify error is mistaken to be `circular structure`. This commit fixes that behaviour, so that other errors like `Do not know how to serialize Bigint` (see https://github.com/blitz-js/babel-plugin-superjson-next/issues/63) aren't swallowed.
* Add integration test
This may be thought of as being a pretty contrived example, but it's exactly what happened in https://github.com/blitz-js/babel-plugin-superjson-next/issues/63.
Co-authored-by: JJ Kasper <jj@jjsweb.site>