Update app.py

app.py

@@ -801,7 +801,15 @@ async(c, o, p, d, n, m, s)=>{
 
 
         var serializedScene = BABYLON.SceneSerializer.Serialize(BABYLON.Engine.LastCreatedScene);
-        var strScene = JSON.stringify(serializedScene, getCircularReplacer());
+        var strScene = JSON.stringify(serializedScene, function(key, val) {
+          if (val != null && typeof val == "object") {
+            if (seen.indexOf(val) >= 0) {
+              return;
+            }
+            seen.push(val);
+          }
+          return val;
+        });
 
         document.getElementById("embed_json").getElementsByTagName("textarea")[0].value = strScene;
         var evt = document.createEvent('Event');