FED-3209 Remove explicit null passed to useRef

[greglittlefield-wf]

Motivation

The null_safety_prep codemod updates cases like useRef<Element>(null) to useRefInit<Element>(null), which, while not incorrect and won't cause issues during migrations, isn't ideal.

Changes

• Handle the explicit null value
• Add tests

Release Notes

Review

See CONTRIBUTING.md for more details on review types (+1 / QA +1 / +10) and code review process.

Please review:

QA Checklist

• Tests were updated and provide good coverage of the changeset and other affected code
• Manual testing was performed if needed
  • Steps from PR author:
    • CI passes
  • Anything falling under manual testing criteria outlined in CONTRIBUTING.md

Merge Checklist

While we perform many automated checks before auto-merging, some manual checks are needed:

• A Frontend Frameworks Design member has reviewed these changes
• There are no unaddressed comments - this check can be automated if reviewers use the "Request Changes" feature
• For release PRs - Version metadata in Rosie comment is correct

[aviary2-wf]

Security Insights

No security relevant content was detected by automated scans.

Action Items

• Review PR for security impact; comment "security review required" if needed or unsure
• Verify aviary.yaml coverage of security relevant code

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Questions or Comments? Reach out on Slack: #support-infosec.

[sydneyjodon-wk]

+10

• CI passes

@Workiva/release-management-p

[rmconsole-wf]

+1 from RM