test: changed var to let in module-errors

PR-URL: #30413
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

Author: jrizza88

test/parallel/test-vm-module-errors.js

@@ -198,7 +198,7 @@ async function checkExecution() {
 // Check for error thrown when breakOnSigint is not a boolean for evaluate()
 async function checkInvalidOptionForEvaluate() {
   await assert.rejects(async () => {
-    const m = new SourceTextModule('export const a = 1; export var b = 2');
+    const m = new SourceTextModule('export const a = 1; export let b = 2');
     await m.evaluate({ breakOnSigint: 'a-string' });
   }, {
     name: 'TypeError',