fix(relayManager): robust check for window.location in getTestRelayOverrides

- Fixes a unit test regression where `getTestRelayOverrides` crashed in Node.js environments (where `window` exists but `window.location` is undefined).
- Updated the check to explicitly verify `window.location` before accessing `.search`.
- Verified via `npm run test:unit:shard2`.

Co-authored-by: PR0M3TH3AN <[email protected]>

js/relayManager.js

@@ -198,7 +198,7 @@ function resolveEntryInput(entry) {
 }
 
 function getTestRelayOverrides() {
-  if (typeof window === "undefined") return null;
+  if (typeof window === "undefined" || !window.location) return null;
 
   const params = new URLSearchParams(window.location.search);
   const paramRelays = params.get("__testRelays__");