refactor: small cleanups (#2059)

* refactor: remove unneeded async

* chore: add express Router type to all routes

* refactor: don't use index in react key

* refactor: correctly get error message in excel route

* refactor: avoid exporting muteable values

apps/server/src/api-data/sheets/sheets.router.ts

@@ -2,7 +2,7 @@
  * This is a feature specific router for integration with google sheets
  */
 
-import express from 'express';
+import express, { Router } from 'express';
 
 import {
   getWorksheetMetadataFromSheet,
@@ -21,7 +21,7 @@ import {
   validateWorksheetMetadata,
 } from './sheets.validation.js';
 
-export const router = express.Router();
+export const router: Router = express.Router();
 
 router.get('/connect', verifyAuthentication);
 router.post('/:sheetId/connect', uploadClientSecret, validateRequestConnection, requestConnection);