fix(AlertBanner): never crash on unknown variant or type — safe fallback - #329
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MihirSachdeva wants to merge 1 commit into
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fix(AlertBanner): never crash on unknown variant or type — safe fallback#329MihirSachdeva wants to merge 1 commit into
MihirSachdeva wants to merge 1 commit into
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When a consumer passes a variant outside the AlertBannerVariant union (e.g. typo "information"), the previous lookup ALERT_BANNER_COLOR_MAPPINGS[type][variant] returned undefined. The component then destructured colors from undefined, throwing a TypeError that crashed the whole subtree behind a React error boundary. The same path inside <Alert /> was affected (it reuses getAlertBannerColors). Wrap variant + type with resolveVariant/resolveType helpers that validate against the enum and fall back to primary/default when unrecognized, emitting a dev-only console.warn so the misuse is still visible during development. The component now renders instead of taking the page down. Two regression specs added in AlertBanner.test.tsx covering unknown variant and unknown type. All Alert + AlertBanner tests pass (19/19). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Why
A consumer in newton-web#8253 passed
variant=\"information\"to<NSAlertBanner>. That string is not in theAlertBannerVariantunion (`'primary' | 'success' | 'warning' | 'error' | 'default'`), so the runtime lookupALERT_BANNER_COLOR_MAPPINGS[type][variant]returnedundefined. The component then destructured{ iconColor, textColor, backgroundColor, borderColor }fromundefined, throwing aTypeErrorthat crashed the entire SemesterFeePayment subtree behind the FE'sErrorBoundary.`` reuses `getAlertBannerColors` and is affected by the same path.
This wasn't caught by TypeScript because the consumer was in a
.jsfile. We want the design system to fail gracefully when this happens — bad colors are much better than a white screen.What
resolveVariant/resolveTypehelpers that validate against the enum and fall back toprimary/defaultwhen the input is not a recognized value.getAlertIconName,getAlertBannerColors, andgetButtonColorFromAlertBannerTypeVariantso any downstream lookup is now always defined.All 19 existing Alert + AlertBanner tests still pass.
Test plan
```bash
npx jest ui/elements/AlertBanner ui/elements/Alert
```
Output:
```
Test Suites: 2 passed, 2 total
Tests: 19 passed, 19 total
```
The two new specs:
does not crash on an unknown variant — falls back to primarydoes not crash on an unknown type — falls back to defaultRisk
Low. Behaviour for valid variant/type is unchanged (same lookup, just with an early-return for known values). Only the previously-crashing path now returns a primary/default-styled banner with a console warning.
🤖 Generated with Claude Code