UI: Add unit tests for errorHandling helpers

[liamkernan]

Summary

Adds Vitest coverage for getErrorStatus and createErrorToaster in src/utils/errorHandling.ts, including the contract that 403 responses do not trigger the shared error toaster (handled by MutationCache).

Testing

npm exec vitest run src/utils/errorHandling.test.ts (from airflow-core/src/airflow/ui)

---

Was generative AI tooling used to co-author this PR?

• No
• Yes

Made with Cursor

[choo121600]

@liamkernan This PR has been converted to draft because it does not yet meet our Pull Request quality criteria.

Issues found:

• ❌ Pre-commit / static checks: Failing: CI image checks / Static checks. Run prek run --from-ref main locally to find and fix issues. See Pre-commit / static checks docs.
• ❌ Other failing CI checks: Failing: Additional PROD image tests / Test e2e integration tests with PROD image / Regular e2e test. Run prek run --from-ref main locally to reproduce. See static checks docs.

What to do next:

• The comment informs you what you need to do.
• Fix each issue, then mark the PR as "Ready for review" in the GitHub UI - but only after making sure that all the issues are fixed.
• There is no rush — take your time and work at your own pace. We appreciate your contribution and are happy to wait for updates.
• Maintainers will then proceed with a normal review.

Converting a PR to draft is not a rejection — it is an invitation to bring the PR up to the project's standards so that maintainer review time is spent productively. There is no rush — take your time and work at your own pace. We appreciate your contribution and are happy to wait for updates. If you have questions, feel free to ask on the Airflow Slack.

[potiuk]

Please follow.our quality expectations