createing a underwater java script ArgumentException: get_fog.

i am getiing two error the first one is

ArgumentException: get_fog can only be called from the main thread. Constructors and field initializers will be executed from the loading thread when loading a scene. Don't use this function in the constructor or field initializers, instead move initialization code to the Awake or Start function. underwater..ctor () (at Assets/Standard Assets/Water (Basic)/underwater.js:15)

the second one is

UnityEngine.RenderSettings:get_fog() underwater:.ctor() (at Assets\Standard Assets\Water (Basic)\underwater.js:15)

the script i have done so far is

function Update () { }//This script enables underwater effects. Attach to main camera.

//Define variables

var underwaterLevel = 102.8067;

// Enable fog RenderSettings.fog = true;

//The scene's default fog settings private var defaultFog; private var defaultFogColor : Color; private var defaultFogDensity : float; private var defaultSkybox : Material; var noSkybox : Material;

function Start () {

 defaultFog = RenderSettings.fog;
 defaultFogColor = RenderSettings.fogColor;
 defaultFogDensity = RenderSettings.fogDensity;
 defaultSkybox = RenderSettings.skybox;

//Set the background color camera.backgroundColor = Color (0, 0.4, 0.7, 1); }

if (transform.position.y < underwaterLevel) {

RenderSettings.fog = true;

RenderSettings.fogColor = Color (0, 0.4, 0.7, 0.6);

RenderSettings.fogDensity = 0.04;

RenderSettings.skybox = noSkybox;

}

else {

RenderSettings.fog = defaultFog;

RenderSettings.fogColor = defaultFogColor;

RenderSettings.fogDensity = defaultFogDensity;

RenderSettings.skybox = defaultSkybox;

}

ANY HELP TO GET RID OF THESE ERRORS WILL BE VERY APPRIECATED

THANKS VERY MUCH IF YOU NEED TO ASK ANY QUESTIONS JUST ASK AHEAD