Further addressed comments by @skatcat31

snippets/chainAsync.md

@@ -10,7 +10,7 @@ const chainAsync = fns => {
   const last = fns[fns.length - 1];
   const next = () => {
     const fn = fns[curr++]
-    fn === last ? fn(undefined) : fn(next);
+    fn === last ? fn() : fn(next);
   }
   next();
 };