fix: respect falsy server snapshots and production context overrides

[OskarEichler]

Fixes

• Honor Provider serverState={0}, false, '', and null instead of silently using the client store's state during server rendering and hydration.
• Honor a connected component's context prop in production. Currently the context assignment is inside the development-only validation block: production either throws when only a custom provider exists or silently selects the default provider's store when both providers exist.

Implementation

Use an explicit undefined check for the optional server snapshot, and move the custom-context assignment outside the development validation guard. The validation itself remains development-only. The diff changes three lines across two files; subscription and selector logic are unchanged.

Verification

• Existing upstream suite: 186 tests across 20 files, with no type errors.
• ESLint, standalone type tests, full package build matrix, targeted Prettier, and git diff --check pass.
• Inline checks against built development and production packages: 38 scenarios covering hooks and connect, falsy/truthy/omitted snapshots, hydration without recoverable errors, post-hydration store updates, custom-only and nested providers, and changing the context prop on a mounted component.
• Before the change, all four falsy snapshots used client state; production custom-only context threw and nested contexts read the wrong store.
• No test files were added or modified. React Doctor flags the existing useSyncExternalStore call inside try/catch; this patch does not alter that error-handling path. Full CI OS/React-version matrices and device tests were not run locally.

Compatibility / breaking changes

No public API, types, dependencies, or supported-platform changes. Explicit falsy server snapshots now take effect as documented; production context overrides now match development behavior. Apps relying on either previous bug will see the corrected state selection. Omitted/undefined snapshots still fall back to store.getState.

[timdorr]

Can you add some tests to both verify the behavior and ensure this doesn't regress in the future?

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/react-redux@1cb1906 -D

yarn add https://pkg.pr.new/react-redux@1cb1906.tgz -D

pnpm add https://pkg.pr.new/react-redux@1cb1906.tgz -D

bun add https://pkg.pr.new/react-redux@1cb1906.tgz -D

commit: 1cb1906

[OskarEichler]

Applied both suggestions: the production-mode context test and falsy serverState test now use Vitest it.for parameterization. The current check suite is green.