# FIX-196 — Controlled→uncontrolled input warning in CheckoutClient

## Fix
`addressToForm()` assigns `addr.postalCode` and `addr.country` directly. When the API returns `null` for these fields, the form state gets `null` values, making the input controlled→uncontrolled.

## Change
`project/frontend/src/components/checkout/CheckoutClient.tsx` line 48-49:
```diff
- postalCode: addr.postalCode,
- country: addr.country,
+ postalCode: addr.postalCode ?? '',
+ country: addr.country ?? '',
```

## Verification
- `npx tsc --noEmit` (frontend): 0 errors
