Fix HMR errors

[dusave]

Closes #

Changelog

New

• Add optional chaining checks to prevent undefined references when hot-module reloading

Changed

Removed

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	98.6 KB (+0.03% 🔺)
packages/react/dist/browser.umd.js	99.03 KB (+0.15% 🔺)

[changeset-bot]

🦋 Changeset detected

Latest commit: f3a5ff2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@primer/react	Patch

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[joshblack]

Just curious, do we know why this ref is undefined when doing our upstream work in dotcom? 🤔 Specifically for HMR. It seems like something is happening with the context value being passed along that's different from how it's being represented in TS?

[camertron]

We think it's because the DOM is being replaced, but honestly that's just a theory 😬

[dusave]

Like @camertron said, we think the DOM is being rebuilt and inserted, which temporarily seems to make the refs undefined. However, it's barely undefined long enough to matter. By the time the page renders, everything is rehydrated and all works fine. But for that split second while it's being swapped out, React throws a fit.

[joshblack]

I would have thought the ref would be stable since it ultimately is coming from useRef and the value returned from that wouldn't be undefined between renders 🤔 (although current totally would if the DOM is changing)

Could it be that the context value (MenuContext) is changing during HMR? It seems like we're explicitly casting this value as being defined in:

react/packages/react/src/ActionMenu/ActionMenu.tsx

Line 255 in f3a5ff2

} = React.useContext(MenuContext) as MandateProps<MenuContextProps, 'anchorRef'>

but with the HMR stuff here that doesn't seem to be the case