Phaser: How to call a function inside another function?

So I actually have the following code that works:

var player;
var box_tnt;

function create (){
    this.physics.add.collider(player, box_tnt, hitTnt, null, this);
}

//the function hitTnt stop the game because the player died
function hitTnt (player, boxes){
   this.physics.pause();
   console.log('Game Over!');
   textGameOver.setText('GAME OVER');
   player.setTint(0xff0000);
   player.anims.play('default');
   gameOver = true;
}

and I want to do something like:

var player;
var box_tnt;

function create (){
    this.physics.add.collider(player, box_tnt, hitTnt, null, this);
}

//the function hitTnt stop the game because the player died
function hitTnt (player, boxes){
    gameOver();
    //other stuff here
}

function gameOver (){
    this.physics.pause();
    console.log('Game Over!');
    textGameOver.setText('GAME OVER');
    player.setTint(0xff0000);
    player.anims.play('default');
    gameOver = true;
}

but I have the following error message:

TypeError: gameOver is not a function

Do you have please any ideas how to do it properly?