refactor: simplify with at

Author: brettz9

lib/node-static.js

@@ -136,7 +136,7 @@ class Server extends events.EventEmitter {
                     req.url ?? '',
                     'http://localhost'
                 ).pathname);
-                if (originalPathname.length && originalPathname.charAt(originalPathname.length - 1) !== '/') {
+                if (originalPathname.length && originalPathname.at(-1) !== '/') {
                     return finish(301, { Location: originalPathname + '/' });
                 } else {
                     this.respond(null, status, headers, [htmlIndex], stat, req, res, finish);