test: remove unused variable from catch

PR-URL: #23477
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/parallel/test-readline-interface.js

@@ -509,7 +509,7 @@ function isWarned(emitter) {
     });
     try {
       fi.emit('data', 'fooX');
-    } catch (e) { }
+    } catch { }
     fi.emit('data', 'bar');
     assert.strictEqual(keys.join(''), 'fooXbar');
     rli.close();