google-home-notifierが気づいたら動かなくなってた時の対処法 ref: https://qiita.com/k_keisuke/items/2974ddaf2bf24a3ea32e

example.js

const serverPort = 8091; // default port
const token = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'; //追加

var deviceName = 'Google Home';
var ip = '192.168.xx.xx'; // default IP

// 中略

app.listen(serverPort, function () {
  ngrok.connect({authtoken: token, addr: serverPort}, function (err, url) { //修正
    console.log('Endpoints:');
    console.log('    http://' + ip + ':' + serverPort + '/google-home-notifier');
// 略
 });
});

package.json

 ~中略~
  "dependencies": {
    "body-parser": "^1.15.2",
    "castv2-client": "^1.1.2",
    "express": "^4.14.0",
-    "google-tts-api": "0.0.2",
+    "google-tts-api": "0.0.4",
    "mdns": "^2.3.3",
    "ngrok": "^2.2.4"
  }
}