[Flight] Fix dev-only crash when passing elements into 3rd party renderers#35690
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`encodeReply` throws "React Element cannot be passed to Server Functions from the Client without a temporary reference set" when a React element is the root value of a `serializeModel` call (either passed directly or resolved from a promise), even when a temporary reference set is provided. The cause is that `resolveToJSON` hits the `REACT_ELEMENT_TYPE` switch case before reaching the `existingReference`/`modelRoot` check that regular objects benefit from. The synthetic JSON root created by `JSON.stringify` is never tracked in `writtenObjects`, so `parentReference` is `undefined` and the code falls through to the throw. This adds a `modelRoot` check in the `REACT_ELEMENT_TYPE` case, following the same pattern used for promises and plain objects. The added `JSX as root model` test also uncovered a pre-existing crash in the Flight Client: when the JSX element round-trips back, it arrives as a frozen object (client-created elements are frozen in DEV), and `Object.defineProperty` for `_debugInfo` fails because frozen objects are non-configurable. The same crash can occur with JSX exported as a client reference. For now, we're adding `!Object.isFrozen()` guards in `moveDebugInfoFromChunkToInnerValue` and `addAsyncInfo` to prevent the crash, which means debug info is silently dropped for frozen elements. The proper fix would likely be to clone the element so each rendering context gets its own mutable copy with correct debug info. closes facebook#34984 closes facebook#35690
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`encodeReply` throws "React Element cannot be passed to Server Functions from the Client without a temporary reference set" when a React element is the root value of a `serializeModel` call (either passed directly or resolved from a promise), even when a temporary reference set is provided. The cause is that `resolveToJSON` hits the `REACT_ELEMENT_TYPE` switch case before reaching the `existingReference`/`modelRoot` check that regular objects benefit from. The synthetic JSON root created by `JSON.stringify` is never tracked in `writtenObjects`, so `parentReference` is `undefined` and the code falls through to the throw. This adds a `modelRoot` check in the `REACT_ELEMENT_TYPE` case, following the same pattern used for promises and plain objects. The added `JSX as root model` test also uncovered a pre-existing crash in the Flight Client: when the JSX element round-trips back, it arrives as a frozen object (client-created elements are frozen in DEV), and `Object.defineProperty` for `_debugInfo` fails because frozen objects are non-configurable. The same crash can occur with JSX exported as a client reference. For now, we're adding `!Object.isFrozen()` guards in `moveDebugInfoFromChunkToInnerValue` and `addAsyncInfo` to prevent the crash, which means debug info is silently dropped for frozen elements. The proper fix would likely be to clone the element so each rendering context gets its own mutable copy with correct debug info. closes facebook#34984 closes facebook#35690
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Ran into a crash in Next.js in
addAsyncInfowithCannot redefine property: _debugInfo.Fix is purely motivated by the types. Need to understand crash conditions and if the defect isn't somewhere higher up.