Update README example

README.md

@@ -7,39 +7,48 @@ A [Portier] client library for Node.js
 ### Example
 
 ```js
-const express = require("express");
-const formParser = require("body-parser").urlencoded({ extended: false });
-const { PortierClient } = require("portier");
+import Fastify from "fastify";
+import formPlugin from "@fastify/formbody";
+import PortierClient from "portier";
 
 const portier = new PortierClient({
   redirectUri: "http://localhost:8000/verify",
 });
 
-const app = express();
+const app = Fastify();
+app.register(formPlugin);
 
 app.get("/", (req, res) => {
-  res.type("html").end(`
+  res.type("text/html");
+  return `
     <p>Enter your email address:</p>
     <form method="post" action="/auth">
       <input name="email" type="email">
       <button type="submit">Login</button>
     </form>
-  `);
+  `;
 });
 
-app.post("/auth", formParser, (req, res) => {
-  portier.authenticate(req.body.email).then((authUrl) => {
-    res.redirect(303, authUrl);
-  });
+app.post("/auth", async (req, res) => {
+  const authUrl = await portier.authenticate(req.body.email);
+  res.redirect(303, authUrl);
 });
 
-app.post("/verify", formParser, (req, res) => {
-  portier.verify(req.body.id_token).then((email) => {
-    res.type("html").end(`
-      <p>Verified email address ${email}!</p>
-    `);
-  });
+app.post("/verify", async (req, res) => {
+  if (req.body.error) {
+    res.type("text/html");
+    return `
+      <p>Error: ${req.body.error_description}</p>
+    `;
+  }
+
+  const email = await portier.verify(req.body.id_token);
+
+  res.type("text/html");
+  return `
+    <p>Verified email address ${email}!</p>
+  `;
 });
 
-app.listen(8000);
+app.listen({ port: 8000 });
 ```