adding dictionary

i am making a word game in which when letters are pressed a word is formed and then will be compare with the Dictionary if the word user provided is valid or not. for that purpose we used a code provided on unity forum by "Jon Petersen " to add Dictionary

#pragma strict

import System.Collections.Generic;
import System.Linq;
var sphe: GameObject;
var myDictionary : Dictionary.<String, String>;
var wordToCheck : String;
function OnMouseDown()
{
if(gameObject.name=="Sphere"){
Update();
}
}
function Awake() 
{
    var MytextAsset = Resources.Load("dictionary", typeof(TextAsset))  as TextAsset;
    myDictionary = MytextAsset.text.Split("

"[0]).ToDictionary(function(w){return w;});
}

function checkWord(word : String) 
{
    return myDictionary.ContainsKey(word);   
}
 
function Update()
{
    if(checkWord(chk1.word))
       Debug.Log(chk1.word + " is a valid word");
    else if(!checkWord(chk1.word))
       Debug.Log(chk1.word + " is NOT a valid word");
}

we added onMouseDown function so when a game object is pressed it start comparing. we are providing the word to compare when the game is running it is giving an error ’

" NullReferenceException: Object reference not set to an instance of an object
dictionary_code.Awake () (at Assets/scripts/dictionary_code.js:17) "
this error on this function

function Awake() 
    {
        var MytextAsset = Resources.Load("dictionary", typeof(TextAsset))  as TextAsset;
        myDictionary = MytextAsset.text.Split("

"[0]).ToDictionary(function(w){return w;});

" NullReferenceException: Object reference not set to an instance of an object
dictionary_code.checkWord (System.String word) (at Assets/scripts/dictionary_code.js:22)
dictionary_code.Update () (at Assets/scripts/dictionary_code.js:27 "
this error on this line

return myDictionary.ContainsKey(word);

don’t know what to do please help.

In addition to the answer by @GameVortex, I’d like to point out that the “as” operator will return null if the object is not of the type specified (TextAsset).

So, either the resource could not be loaded because Resources.Load returned null, or "as TextAsset " returned null.

In either case, you want to add a check for null before referencing MyTextAsset on line 17, which is a good practice in general.