fix: guard against missing context in useFeatureFlag

[francinelucca]

Relates to #8114

This pull request makes a small improvement to the useFeatureFlag hook to make it more robust against missing context. Now, if the FeatureFlagContext is not available, the hook will safely return false instead of throwing an error.

Changelog

Changed

• Guard against missing context in useFeatureFlag

Rollout strategy

• Patch release
• Minor release
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Testing & Reviewing

[changeset-bot]

🦋 Changeset detected

Latest commit: ce8e0e3

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

This PR includes changesets to release 1 package

Name	Type
@primer/react	Patch

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[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. If this doesn't work, you can also use the original workflow here. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

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[Copilot]

Pull request overview

This PR hardens the useFeatureFlag hook so it no longer crashes rendering when FeatureFlagContext is unexpectedly missing (e.g. due to duplicate/partial @primer/react bundles), aligning with the issue report in #8114.

Changes:

• Make useFeatureFlag resilient to a missing context by returning false instead of throwing.

Show a summary per file

File	Description
packages/react/src/FeatureFlags/useFeatureFlag.ts	Adds an optional chaining + nullish-coalescing guard to avoid runtime throws when context is missing.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 2
• Review effort level: Low

[primer]

🤖 Lint issues have been automatically fixed and committed to this PR.

[primer-integration]

Integration test results from github/github-ui PR:

  CI Passed
  VRT Passed
  Projects Passed

All checks passed!