Null Reference at (wrapper managed-to-native)

What do they mean ?

So i was build a game and give it to my friend. I play it here was okay, no problem, no (wrapper managed-to-native), but when he play in his computer, he always got this messages and the game starts crazy (sometimes the object disappear, and appear). We use same Processor (Intel), same Graphic Card (nVidia), and same OS (Windows 7)

This is what i got from his OutputLog

 NullReferenceException
   at (wrapper managed-to-native) UnityEngine.GameObject:Internal_AddComponentWithType (System.Type)
   at UnityEngine.GameObject.AddComponent (System.Type componentType) [0x00000] in <filename unknown>:0 
   at AIKart.ReleaseNitro () [0x00000] in D:\Black Samba\NitroRacerXD\Assets\SKIPPER\Skript\CORE\AIKart.js:463 
   at AIKart+$UseWeaponNos$425+$.MoveNext () [0x001b7] in D:\Black Samba\NitroRacerXD\Assets\SKIPPER\Skript\CORE\AIKart.js:1047 

And this is the script

 function ReleaseNitro(){
     newNitroTrailer.AddComponent(KillYou);
     newNitroTrailer.GetComponent(KillYou).lifeTime = 6;
     useNitro = false;
     nosObject.SetActive(false);
     nosObject.audio.clip = null;
     maxSpeed = awakeMaxSpeed;
 }
 
 function UseWeaponNos(howMuch : int){
     newNitroTrailer = Instantiate(nosObject,nosObject.transform.position,nosObject.transform.rotation);
     newNitroTrailer.SetActive(true);
     newNitroTrailer.GetComponent(TrailRenderer).enabled = true;
     useNitro = true;
     
     maxSpeed = 10000;
     nosObject.SetActive(true);
     nosObject.GetComponent(TrailRenderer).enabled = false;
     nosObject.audio.clip = sfx[0];
     yield;
     usableNitro = false;
     if(!nosObject.audio.isPlaying && nosObject.audio.clip != null && usableNitro)nosObject.audio.Play();
     
     yield new WaitForSeconds(howMuch);
     useNitro = false;
     usableNitro = true;
     ReleaseNitro();
 }

Please help. Thanks for any answers.