Summary

Dashboard fails to load with the error banner:

Failed to load dashboard: e is not iterable

Triggered when one of the dashboard data sources returns a non-array shape that the renderer then tries to iterate (for…of, .map, spread, Promise.allSettled over a non-array, etc.).

Likely fault site

frontend/src/dashboard.ts loadDashboard() — the try block at lines 95–115 calls renderDashboardSummary, renderSavingsChart, renderUpcomingPurchases, then loadSavingsTrendChart, then renderFreshness. The e is not iterable shape is most consistent with one of:

• summaryData.by_service not being an object → handled by || {} fallback at line 98.
• upcomingData.purchases not being an array → handled by || [] fallback at line 99.
• loadSavingsTrendChart / renderFreshness iterating over a missing array.
• The recommendations fetch added in feat(frontend/dashboard): Potential Monthly Savings card mirrors Recommendations-page range (closes #293) #295 (Dashboard Potential Monthly Savings parity) iterating over a Promise.allSettled result that's actually a single rejected promise / non-array.

The minified e symbol points at a callee — not the body of loadDashboard itself — so the next debug step is to log the unminified stack from a deployed build, or run locally with vite preview and reproduce.

Acceptance criteria

• Repro the error consistently in dev (likely with an empty backend or one provider returning a 5xx).
• Add defensive Array.isArray(...) / nullish-coalescing guards at every call site that iterates dashboard data.
• Catch + soft-fail in non-critical widgets (savings trend, freshness) so a single failing widget doesn't blank the dashboard.
• Regression test in frontend/src/__tests__/dashboard.test.ts covering: (a) summaryData payload missing the iterable field, (b) one of the parallel fetches rejecting.