lib: fix eslint early return

The nodejs#45243 upgraded eslint
and apparently, when you specific a `@returns` early returns
aren't considered valid. This PR fixes this lint issue.

lib/events.js

@@ -1091,8 +1091,6 @@ function on(emitter, event, options) {
       { once: true });
   }
 
-  return iterator;
-
   function abortListener() {
     errorHandler(new AbortError(undefined, { cause: signal?.reason }));
   }
@@ -1120,4 +1118,5 @@ function on(emitter, event, options) {
 
     iterator.return();
   }
+  return iterator;
 }