fix: handle non-configurable window.Shopify from browser extensions (#3575)

[AndrianBalanescu]

Fix: "Cannot redefine property: Shopify" crash with browser extensions (#3575)

Problem

Browser extensions like Urban VPN define window.Shopify as a non-configurable property. When Hydrogen's customer privacy API tries to call Object.defineProperty(window, 'Shopify', ...), it throws a TypeError: Cannot redefine property: Shopify, crashing the entire Hydrogen app for affected users.

This has been confirmed by multiple users in #3575 since March 2026.

Solution

As suggested by @frandiox in this comment, the fix avoids relying on Object.defineProperty being successful:

1. Wrap Object.defineProperty(window, 'Shopify', ...) in a try/catch — if the property is non-configurable, the error is caught gracefully instead of crashing the app.

2. Fall back to polling — when defineProperty fails, a lightweight polling mechanism (every 50ms, cleaned up after 30s) monitors window.Shopify for the customerPrivacy assignment and applies the same override logic.

3. Extracted shared override function — the customerPrivacy getter/setter logic is extracted into overrideCustomerPrivacy(), used by both the defineProperty path and the polling fallback, ensuring consistent behavior.

The previous PR #3576 was closed without merge. This PR takes the maintainer-suggested approach and includes a fallback for maximum resilience.

Testing

• All 9 existing tests pass unchanged
• Added a new test simulating a non-configurable window.Shopify (as browser extensions create), verifying the hook does not crash and still processes customerPrivacy via the polling fallback

✓ src/customer-privacy/useCustomerPrivacy.test.tsx (10 tests) 135ms
Tests  10 passed (10)

Changeset

• @shopify/hydrogen: patch

Fixes #3575

[AndrianBalanescu]

Cycle 520 QA: Fixed polling cleanup leak in the non-configurable window.Shopify fallback path. The setInterval (50ms) and setTimeout (30s) created in the polling fallback were never cleaned up on component unmount, causing memory leaks and potential state updates on unmounted components. Added cleanupPolling function returned from useEffect that clears both timers, matching the cleanup pattern used by other useEffect hooks in the same file. All 10 tests still pass.