Unity editor crashes after LoadSceneAdditive or LoadLevelAdditiveAsync

I always have a unity crash when I attempt to do LoadSceneAdditive or LoadLevelAdditiveAsync.

I have 5 scenes :

• Root : Contains a camera and a emptyGameObject with my component "Loaded"

• streamed1 : a sphere

• streamed2 : a capseul

• streamed3 : a sphere

• streamed4 : a 3dText with a custom font

I build a scene asset bundle :

 string[] levels = new string[] { "Assets/streamed1.unity", "Assets/streamed2.unity", "Assets/streamed3.unity", "Assets/streamed4.unity" };
 BuildPipeline.BuildStreamedSceneAssetBundle( levels, "Assets/StreamingAssets/streamed.unity3d", BuildTarget.WebPlayerStreamed); 

My component Loaded

 using UnityEngine;
 using System.Collections;
 
 public class Loaded : MonoBehaviour {
 
     // Use this for initialization
     IEnumerator Start () {
         #if UNITY_EDITOR
         string filePath = "file:///" + Application.streamingAssetsPath+"/streamed.unity3d";
     #elif UNITY_WEBPLAYER
             string filePath = System.IO.Path.Combine( "StreamingAssets", "streamed.unity3d");
     #else
             string filePath = System.IO.Path.Combine(Application.streamingAssetsPath, "streamed.unity3d");
     #endif    
         
         WWW www = new WWW(filePath);
         yield return www;
         
         AssetBundle asset = www.assetBundle ; // Pour que ça marche
         
         Debug.Log("load OK") ;
         
         for (int i = 1 ; i < 5 ; i++) {
             float progress = Application.GetStreamProgressForLevel("streamed"+i) ;
             while (!Application.CanStreamedLevelBeLoaded("streamed"+i)) {
                 progress = Application.GetStreamProgressForLevel("streamed"+i) ;
                 Debug.Log("wait ("+Mathf.Round(progress * 100)+"%)") ;
                 yield return new WaitForSeconds(0.1f) ;
             }
             
             Debug.Log("scene ready") ;
             Application.LoadLevelAdditive("streamed"+i) ;
             /*AsyncOperation async = Application.LoadLevelAdditiveAsync("streamed"+i) ;
             
             while (!async.isDone) {
                 Debug.Log("prepare scene"+i) ;
                 yield return new WaitForSeconds(0.1f) ;
             }*/
         }
         
         Debug.Log("finished") ;
     }
 }

The crash comes after the load scene streamed4.

What can I do now ?

Thanks