fix: Proper message with types

src/routes/(auth)/cart/+page.server.ts

@@ -24,8 +24,7 @@ export const load: PageServerLoad = async ({ fetch, cookies }) => {
 		};
 	} catch (err) {
 		return {
-			// @ts-expect-error as message is an empty object
-			message: err.message,
+			message: err instanceof Error ? err?.message : 'Unknown error',
 			status: 'error'
 		};
 	}