process: replace vars in per_thread.js

PR-URL: #30385
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>

Author: EmaSuriano

lib/internal/process/per_thread.js

@@ -167,7 +167,7 @@ function wrapProcessMethods(binding) {
   }
 
   function kill(pid, sig) {
-    var err;
+    let err;
 
     // eslint-disable-next-line eqeqeq
     if (pid != (pid | 0)) {