Hello.
Phaser.Types.GameObjects.Graphics.Options does not have the “fSize” field:

It is from the digitsensitive’s Snake game example: https://github.com/digitsensitive/phaser3-typescript/blob/master/src/games/snake/objects/apple.ts
export class Apple extends Phaser.GameObjects.Graphics {
constructor(scene, params) {
super(scene, params);
this.x = params.xPos;
this.y = params.yPos;
this.fillStyle(0x61e85b, 0.8);
this.fillRect(params.fSize, params.fSize, params.fSize, params.fSize);
this.scene.add.existing(this);
}