title: I can not read the data on Firebase Functions
body: <p>I use firebase functions for push notification triggers.</p>
  
  <p>I can send notifications but I cannot read some data when the trigger launches.</p>
  
  <p>I tried usual firebase database functions but they didn't work.</p>
  
  <pre><code>const admin = require('firebase-admin')
  admin.initializeApp(functions.config().firebase)
  
  let fcm = ''
  exports.sendNewMessageNotification = functions.database.ref('/xxx/userInformations/{uid}/')
      .onWrite((change:any) =&gt; {
      // console.log(change.before)
        const payload = {
            notification: {
                title: 'Kahve Falı',
                body: 'Falın geldi!',
        }
      }
      admin.database().ref('/xxx/userInformations/{uid}/fortunes')
      .once('value')
      .then((snapshot:any) =&gt; {
        console.log('snapshot.val()')//I want to get that snaphot.val()
  
        });
        fcm = change.before._data.fcm;
        return admin.messaging().sendToDevice(fcm, payload);
      });
  </code></pre>
  
  <p>It doesn't read that snapshot. It returns null or undefined with different ways. 
  And I can not make this line like that;
  <code>.then((snapshot) =&gt; {</code></p>
  
  <p>If I don't put <code>:any</code> it gives me an error on VS Code.</p>