Uncaught TypeError: Cannot read properties of undefined (reading 'sys') at initialize.setTexture

Phaser 3
1

I am using Phaser version 3.55.2, what is wrong here? Does Phaser not allow to pass scene as parameter and restart on that? I am new to Phaser. plz help me to figure out what is going on here. Thank you.

var config = {
    type: Phaser.AUTO,
    parent: 'phaser-example',
    width: innerWidth * 0.9,
    height: innerHeight * 0.9,
    scene: [Level],
    backgroundColor: 0xE4004D
}
const game = new Phaser.Game(config);

class Level extends Phaser.Scene {
    constructor() {
        super("bubbleSort")
    }
    create(){
        .......
        this.event=new UserEventHandler({ctx:this})
        this.event.createRestartBtn(0,0);
    }
}

class UserEventHandler {
    constructor(con) {
        this.ctx = con.ctx;
    }
    createRestartBtn(x, y) {
        this.rst = this.ctx.add.text(x, y, 'Restart', {
            font: '30px CustomFont',
            fill: '#f1c27d',
            align: 'center'
        });
        this.rst.setOrigin(0.5, 0.5); 

        this.rst.setInteractive({ useHandCursor: true });
        this.rst.on('pointerover', () => {
            this.rst.setFill('#ffffff')
            this.rst.setFontSize(35)
        });
        this.rst.on('pointerout', () => {
            this.rst.setFill('#f1c27d')
            this.rst.setFontSize(30)
        });

        this.rst.on('pointerdown',()=>{
            this.ctx.scene.restart();
        });
    }
}
2

What’s the stack trace?

I tried this code, clicked the button a few times, and got no errors.