Named examples are returned as '[object Object]' #97

Description

When a named example is picked through ?example=name, the object value is not returned as JSON, the response simply says '[object Object]'.

I've provided a fix + test in https://github.com/jonaskuske/msw-source/tree/fix/stringify-named-example-object (before I saw that PRs are restricted here), feel free to merge from there :)

Reproduction steps

See https://github.com/jonaskuske/msw-source/blob/fix/stringify-named-example-object/src/open-api/utils/open-api-utils.test.ts#L85

Expected behavior

A JSON response.

Initial assessment

JSON.stringify is only called in the branch that picks the first example (no name provided), not in the case where a name is provided so the named example is picked.