## Summary
With https://github.com/facebook/react/pull/26349 we now serialize
`undefined`. However, deserializing it on the client is currently
indistinguishable from the value missing entirely due to how
`JSON.parse` treats `undefined` return value of reviver functions.
This leads to inconsistent behavior of the `Object.hasOwn` or `in`
operator (used for narrowing in TypeScript). In TypeScript-speak, `{
prop: T | undefined}` will arrive as `{ prop?: T }`.
## How did you test this change?
- Added test that is expected to fail. Though ideally the implementation
of the component would not care whether it's used on the client or
server.
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