Firebase: adminがUnexpected Tokenとして認識される

Firebase Cloud Functionを以下のサイトで勉強しています。

https://codelabs.developers.google.com/codelabs/firebase-cloud-functions/#9

チュートリアルにあるコード

javascript
1// Import the Firebase SDK for Google Cloud Functions.
2const functions = require('firebase-functions');
3// Import and initialize the Firebase Admin SDK.
4const admin = require('firebase-admin');
5admin.initializeApp();
6
7// Sends a notifications to all users when a new message is posted.
8exports.sendNotifications = functions.database.ref('/messages/{messageId}').onCreate(
9    async (snapshot) => {
10      // Notification details.
11      const text = snapshot.val().text;
12      const payload = {
13        notification: {
14          title: `${snapshot.val().name} posted ${text ? 'a message' : 'an image'}`,
15          body: text ? (text.length <= 100 ? text : text.substring(0, 97) + '...') : '',
16          icon: snapshot.val().photoUrl || '/images/profile_placeholder.png',
17          click_action: `https://${process.env.GCLOUD_PROJECT}.firebaseapp.com`,
18        }
19      };
20
21      // Get the list of device tokens.
22      const allTokens = await admin.database().ref('fcmTokens').once('value');
23      if (allTokens.exists()) {
24        // Listing all device tokens to send a notification to.
25        const tokens = Object.keys(allTokens.val());
26
27        // Send notifications to all tokens.
28        const response = await admin.messaging().sendToDevice(tokens, payload);
29        await cleanupTokens(response, tokens);
30        console.log('Notifications have been sent and tokens cleaned up.');
31      }
32    });

の最後の部分を以下のように変更したところ、タイトルのエラーが出ました。

javascript
1// Sends a notifications to all users when a new message is posted.
2exports.sendNotifications = functions.database.ref('/messages/{messageId}').onCreate(
3    async (snapshot) => {
4      // Notification details.
5      const text = snapshot.val().text;
6      const payload = {
7        notification: {
8          title: `${snapshot.val().name} posted ${text ? 'a message' : 'an image'}`,
9          body: text ? (text.length <= 100 ? text : text.substring(0, 97) + '...') : '',
10          icon: snapshot.val().photoUrl || '/images/profile_placeholder.png',
11          click_action: `https://${process.env.GCLOUD_PROJECT}.firebaseapp.com`,
12        }
13      };
14
15      terminateNotification();   
16
17    });
18
19function terminateNotification() {
20	// get list of device tokens
21	const allTokens = await admin.database().ref('fcmTokens').once('value');
22	if (allTokens.exists()) {
23		// listing all tokens to send notification
24		const tokens = Object.keys(allTokens.val());
25
26		// send notification to all tokens
27		const response = await admin.messaging().sendToDevice(tokens, payload);
28		await cleanupTokens(response, tokens);
29		console.log('notifications sent & tokens cleand up');
30	}
31}