Authentication Error on first run

Hi,

I tried to use this example of AWS Kinesis Video Streams with Cognito, but I am experiencing a problem, where on the first load of the page, the correct credentials result in an authentication error. I am sure that the username and password combination is right because on the second try the same saved credentials work. The problem is mostly reproducible.

In the DevTools, I see the following errors:

Error POST https://cognito-identity.eu-central-1.amazonaws.com/ 400
NotAuthorizedException: Logins don't match. Please include at least one valid login for this identity or identity pool.

After trying to understand the problem, I found this comment in the example code:

amazon-kinesis-video-streams-webrtc-sdk-js-with-amazon-cognito/examples/master.js

Lines 37 to 43 in f4acccc

    
           var cognitoUser = new AmazonCognitoIdentity.CognitoUser(userData); 
        
           //console.log(AWS.config.credentials.accessKeyId) 
        
           //this is the call where it throws an error in the first run 
        
           cognitoUser.authenticateUser(authenticationDetails, { 
        
               onSuccess: function(result) {

The above comment describes the problem very good.

I tried to do some debugging and found out that the onSuccess function in line 43 is reached before the error is produced.

Does anyone know how to fix this error and help others getting started with this tutorial?

Greetings,
Fabio

	var cognitoUser = new AmazonCognitoIdentity.CognitoUser(userData);

	//console.log(AWS.config.credentials.accessKeyId)

	//this is the call where it throws an error in the first run
	cognitoUser.authenticateUser(authenticationDetails, {
	onSuccess: function(result) {