YouTube Data API v3 invalid page token

I am trying to request the messages of a live-stream chat via Youtube Data API V3. The problem is that it didn't find the page token. I get following error:

{"error": {"code": 400,"message": "page token is not valid.","errors": [{"message": "page token is not valid.","domain": "youtube.liveChat","reason": "pageTokenInvalid"    }]  }}

This is my JS:

gapi.load('client', start);function start() {  fetch('config.json')    .then(response => response.json())    .then(config => {      gapi.client.init({        apiKey: config.apiKey,        discoveryDocs: ["https://www.googleapis.com/discovery/v1/apis/youtube/v3/rest"]      }).then(function() {        var liveChatId = config.liveChatId;        function getChatMessages(pageToken) {          gapi.client.youtube.liveChatMessages.list({            liveChatId: liveChatId,            part: 'snippet',            pageToken: pageToken          }).then(function(response) {            var chatDiv = document.getElementById('chat');            response.result.items.forEach(function(item) {              var message = item.snippet.displayMessage;              var messageElement = document.createElement('div');              messageElement.className = 'chat-message';              messageElement.textContent = message;              chatDiv.appendChild(messageElement);              setTimeout(function() {                messageElement.style.transform = 'translateX(100%)';                setTimeout(function() {                  chatDiv.removeChild(messageElement);                }, 500);              }, 10000);            });            if (response.result.nextPageToken) {              getChatMessages(response.result.nextPageToken);            }          });        }        getChatMessages();      });    }).catch(error => {      console.error('Fehler beim Laden der Konfigurationsdatei: '+ error);    });}