fix: prevent TypeError in serialize_refreshes when state.refreshes is null

Fixes issue where remote function redirects would crash with 'TypeError: Cannot convert undefined or null to object' when calling Object.keys() on undefined state.refreshes.

This happens when redirect() is called in remote functions and serialize_refreshes tries to process refresh data that doesn't exist.

The fix adds a fallback to an empty object when state.refreshes is null/undefined.

Author: robinbraemer

packages/kit/src/runtime/server/remote.js

@@ -194,7 +194,7 @@ async function handle_remote_call_internal(event, state, options, manifest, id)
 	 * @param {string[]} client_refreshes
 	 */
 	async function serialize_refreshes(client_refreshes) {
-		const refreshes = /** @type {Record<string, Promise<any>>} */ (state.refreshes);
+		const refreshes = /** @type {Record<string, Promise<any>>} */ (state.refreshes || {});
 
 		for (const key of client_refreshes) {
 			if (refreshes[key] !== undefined) continue;