Update load_cesium.js

public/load_cesium.js

 var viewer = new Cesium.Viewer('cesiumContainer');
+Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiJmMGJkYzQwZS1lNTI2LTQ1N2UtYjEyNy1lMjJiYjg2YjIxYmQiLCJpZCI6MTcxNDQsInNjb3BlcyI6WyJhc3IiLCJnYyJdLCJpYXQiOjE1NzE3Mjc2Njl9.C_XxMaj0_rAu-ADAkpcjcdzcccEMZ-cdbcn4fi5qby8';
 var tileset = viewer.scene.primitives.add(new Cesium.Cesium3DTileset({
     // url: "../3dtile_nyc/tileset.json",
     // url: "http://193.196.37.89:8092/AssetsHFT/3DTile_Niedernhalle/tileset.json",