Problem reading from array at runtime

Ok, so basically I am making a game engine, and am having it so it reads from a code file at runtime. This is a short snippet that is causing the problem: (varList is a string, varArray is an array, I am splitting spaces to read the code file, so str is the string after the first space, the cases is the word before the first space)

 case "var":
             varList = varList + str + "|";
             varArray = varList.ToString().Split("|"[0]);
             
         case "getkey":
             var varIndex : int = 999;
             var error : boolean = false;
             var isDone : boolean = false;
             for (var iCount : int = 0; iCount < varArray.Length; iCount++) {
                 
                 if (varArray[iCount] == str && isSub && error == false && isDone == false) {
                     
                     varIndex = iCount;
                     error = false;
                     isDone = true;
                     
                 }
                 
             }
             
             if (error || isDone == false || varIndex == 999) {
                 
                 print("Variable, '" + str + "' not found!");
                 
             } else {
                 
                 var key;
                 
                 while (key == "") {
                     
                     key = Input.anyKeyDown;
                     
                 }
                 
                 print("Key pressed : " + key.ToString());
             }
             break;

sorry, formatting a bit messed up, but basically its throwing this error repetitively: NullReferenceExceptioon: Object reference not set to instance of an object Boo.Lang.Runtime>RuntimeServices.InvokeBinaryOperator (System.String operatorName, System.Object lhs System.Object rhs)

Referring to the line of code: varList = varList + str + "|";