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

You scrambled the code lines. The correct order should be:

//This script enables underwater effects. Attach to main camera.

//Define variables

var underwaterLevel = 102.8067;

//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);
}

function Update () {
  if (transform.position.y < underwaterLevel) {
    // Enable fog
    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;
  }
}