style(eslint): fix no-unassigned-vars no-useless-assignment preserve-caught-error (#21175)

* fix: fix no-unassigned-vars

* fix: fix preserve-caught-error

* fix: fix no-useless-assignment

* fix: update variable types for better type safety

* fix: replace nullish coalescing with logical OR for limit assignment

* fix: add DataItem type import for better type safety

scripts/workflow/test-route/identify.mjs

@@ -10,7 +10,7 @@ export default async function identify({ github, context, core }, body, number,
     const bodyNoCmts = body?.replaceAll(/<!--[\S\s]*?-->/g, '');
     const m = bodyNoCmts?.match(/```routes\s+([\S\s]*?)```/);
     core.debug(`match: ${m}`);
-    let routes = null;
+    let routes;
 
     const issueFacts = {
         owner: context.repo.owner,