Which object reference is not set to an object instance?

So in "SentenceDisplayScript I create some text and try to at the same time, send that text as a string to another script, which is on the same object.

I've encountered various bugs but the constant one that I can't understand, is this "NullReferenceException: Object reference not set to an instance of an object ... ... ... SentenceDisplayScript:Main() (at Assets/scripts/SentenceDisplayScript.js:27)"

Line 27 is "SpeakingScript.use.WordChecker(guiText.text);"

The use of the static variable used to work. I changed something, though I can't figure out what and now it just gives me this error.

I've read elsewhere that I should avoid the use of static variables and use GetComponent instead. But I can't figure out how to use that for this purpose. Anyway, that's besides the point.

Does anyone know what I'm doing wrong?

SentenceDisplayScript

 function Start () {
 
     guiText.text = "I eat tall green\n people that I like";
 
     SpeakingScript.use.WordChecker(guiText.text);
 
 }

SpeakingScript.js

 private var pronoun : String [] =  ["i", "me", "tall"];
 private var adjective : String [] = ["green", "tall"];
 private var verb : String [] = ["like", "eat"];
 private var sentence : String;
 var proBlock : Transform;
 var adjBlock : Transform;
 var verbBlock : Transform;
 static var use : SpeakingScript;

 function WordChecker (sentence : String) {
     while (true){
         sentence = sentence.ToLower(); // make the string lower case so we can search for the keywords case-insensitive.
         var words : String [] = sentence.Split (" "[0]);
         for (y = 0; y < words.Length; y++) {
             for (x = 0; x < pronoun.Length; x++){  
                 if (pronoun[x] == words[y] && Input.GetKey("w"))
                 var pronoun = Instantiate (proBlock, Vector3(x,1,1), Quaternion.identity) as Transform;
             }
             for(z = 0; z < adjective.Length; z++){
                 if (adjective[z] == words[y])
                 var adjective = Instantiate (adjBlock, Vector3(1,z,1), Quaternion.identity) as Transform;
             }
             for(w = 0; w < verb.Length; w++){
                 if (verb[w] == words[y])    
                 var verb = Instantiate (verbBlock, Vector3(1,2,w), Quaternion.identity) as Transform;
             }
             if (x > pronoun.Length && z > adjective.Length && w > verb.Length)
                 break;
             yield;
         }
     }
 }