Encountering an error while attempting to create a game - actionscript-3

Question

I'm trying to create a crossword puzzle game using Actionscript 3.0 in Adobe
Animate. For the game coding, I followed an online tutorial and now I'm encountering an error. The error occurs whenever I'm in the actual game scene, no errors are encountered on the home page or instruction page. can anyone help me? my coding skills are below basic.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at CROSSWORD_CODE_fla::MainTimeline/entFrame().
stop();
quitbtn.addEventListener(MouseEvent.CLICK, quitt);
function quitt(evt: MouseEvent): void {
gotoAndStop("start");
}
var hippopotamus: Number = 0;
var horse: Number = 0;
var eel: Number = 0;
var frog: Number = 0;
var ant: Number = 0;
var turtle: Number = 0;
var tiger: Number = 0;
var bird: Number = 0;
var penguin: Number = 0;
var orca: Number = 0;
var octopus: Number = 0;
var owl: Number = 0;
var snail: Number = 0;
var duck: Number = 0;
var kangaroo: Number = 0;
var iguana: Number = 0;
var ALLwords:Number = 0;
var Total:Number = 0;
{
stage.addEventListener(Event.ENTER_FRAME, entFrame);
function entFrame(evt:Event):void {
if ((hypoH.text == ("h").toString())
&& (hypo1.text == ("i").toString())
&& (hypoP.text == ("p").toString())
&& (hypoP2.text == ("p").toString())
&& (hypoO.text == ("o").toString())
&& (hypoP3.text == ("p").toString())
&& (hypoO2.text == ("o").toString())
&& (hypoT.text == ("t").toString())
&& (hypoA.text == ("a").toString())
&& (hypoM.text == ("m").toString())
&& (hypoU.text == ("u").toString())
&& (hypoS.text == ("s").toString()))
{
hippopotamus = 1;
trace("hippopotamus");
}
}
{
if ((hrsO.text == ("o").toString())
&& (hrsR.text == ("r").toString())
&& (hrsS.text == ("s").toString())
&& (hrsE.text == ("e").toString()))
{
horse = 1;
trace("horse");
}
}
{
if ((eelE.text == ("e").toString())
&& (eel1.text == ("l").toString()))
{
eel = 1;
trace("eel");
}
}
{
if ((penP.text == ("p").toString())
&& (penE.text == ("e").toString())
&& (penN.text == ("n").toString())
&& (penG.text == ("g").toString())
&& (penU.text == ("u").toString())
&& (pen1.text == ("i").toString())
&& (penN2.text == ("n").toString()))
{
penguin = 1;
trace("penguin");
}
}
{
if ((brdB.text == ("b").toString())
&& (brdR.text == ("r").toString())
&& (brdD.text == ("d").toString()))
{
bird = 1;
trace("bird");
}
}
{
if ((octO.text == ("o").toString())
&& (octC.text == ("c").toString())
&& (octT.text == ("t").toString())
&& (octO2.text == ("0").toString())
&& (octP.text == ("p").toString())
&& (octU.text == ("u").toString()))
{
octopus = 1;
trace("octopus");
}
}
{
if ((orcR.text == ("r").toString())
&& (orcC.text == ("c").toString())
&& (orcA.text == ("a").toString()))
{
orca = 1;
trace("orca");
}
}
{
if ((owlO.text == ("o").toString())
&& (owlW.text == ("w").toString()))
{
owl = 1;
trace("owl");
}
}
{
if ((nailS.text == ("s").toString())
&& (nailA.text == ("a").toString())
&& (nail1.text == ("i").toString())
&& (nailL.text == ("l").toString()))
{
snail = 1;
trace("snail");
}
}
{
if ((dkD.text == ("d").toString())
&& (dkU.text == ("u").toString())
&& (dkC.text == ("c").toString())
&& (dkK.text == ("k").toString()))
{
duck = 1;
trace("duck");
}
}
{
if ((groA.text == ("a").toString())
&& (groN.text == ("n").toString())
&& (groG.text == ("g").toString())
&& (groA2.text == ("a").toString())
&& (groR.text == ("r").toString())
&& (groO.text == ("o").toString()))
{
kangaroo = 1;
trace("kangaroo");
}
}
{
if ((frgF.text == ("f").toString())
&& (frgR.text == ("r").toString())
&& (frgG.text == ("g").toString()))
{
frog = 1;
trace("frog");
}
}
{
if ((ignG.text == ("g").toString())
&& (ignU.text == ("u").toString())
&& (ignA.text == ("a").toString())
&& (ignN.text == ("n").toString()))
{
iguana = 1;
trace("iguana");
}
}
{
if ((antA.text == ("a").toString())
&& (antN.text == ("n").toString()))
{
ant = 1;
trace("ant");
}
}
{
if ((trtT.text == ("t").toString())
&& (trtU.text == ("u").toString())
&& (trtR.text == ("r").toString())
&& (trtT2.text == ("t").toString())
&& (trtL.text == ("l").toString()))
{
turtle = 1;
trace("turtle");
}
}
{
if ((tgr1.text == ("i").toString())
&& (tgrG.text == ("g").toString())
&& (tgrE.text == ("e").toString()))
{
tiger = 1;
trace("tiger");
}
}
ALLwords = hippopotamus + horse + eel + frog + tiger + octopus + penguin + bird + orca +
turtle + duck + snail + ant + kangaroo + iguana + owl;
Total = 16 - ALLwords;
if (Total == 0)
{
trace("Gameover");
}
incorrectTXT.text = ("you have" + Total+ " incorrect words remaining").toString();
}