# \[SOLVED\] Cannot read property 'isParent' of undefined

**URL:** <https://phaser.discourse.group/t/solved-cannot-read-property-isparent-of-undefined/2119>\
**Category:** Phaser 3\
**Created:** [April 15, 2019, 10:22pm UTC](https://phaser.discourse.group/t/solved-cannot-read-property-isparent-of-undefined/2119 "2019-04-15T22:22:54Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![facecjf](https://yyz2.discourse-cdn.com/free1/user_avatar/phaser.discourse.group/facecjf/32/455_2.png) [@facecjf](https://phaser.discourse.group/u/facecjf)\
**Post date:** [April 15, 2019, 10:22pm UTC](https://phaser.discourse.group/t/solved-cannot-read-property-isparent-of-undefined/2119/1 "2019-04-15T22:22:54Z")

</div>

I am currently working on a mini game. 90% of the time everything works as intended. I sometimes get the error :

`World.js:1855 Uncaught TypeError: Cannot read property 'isParent' of undefined at World.collideObjects (World.js:1855) at World.collide (World.js:1832) at Scene.update (index.js:387) at Systems.step (Systems.js:371) at SceneManager.update (SceneManager.js:562) at Game.step (Game.js:474) at TimeStep.step (TimeStep.js:558) at step (RequestAnimationFrame.js:105)`

My code

`function update () { if (startGame) { dragonFlapShadow.visible = true dragonFlapShadow.setPosition(dragonFlap.x + 60, dragonFlap.y + 240) }`

```
this.physics.world.collide(killZone, wallCenter, atkCollision)

this.physics.world.collide(killZone, noKillZone, noAtkCollision)

killZone.setPosition(dragonFlap.x + 120, dragonFlap.y)

killZone.body.debugBodyColor = killZone.body.touching.none ? 0x35e0ff : 0xff1938

if (dragAtk && canAtk && startGame) {
    dragonFire.visible = true
    dragonFire.setPosition(dragonFlap.x, dragonFlap.y)

} else if (!dragAtk && startGame && canAtk) {
    dragonFire.visible = false
    wallCenter.tint = 0xffffff
    wallCenter.body.debugBodyColor = 0x35e0ff
    canAtk = false
}

if (dragMoveTo) {
    this.physics.moveToObject(dragonFlap, target, 600, 200)
    dragAtk = false
}

let distance = Phaser.Math.Distance.Between(dragonFlap.x, dragonFlap.y, target.x, target.y)
if (dragonFlap.body.speed > 0)
{
    if (distance < 4)
    {
        dragonFlap.body.reset(target.x, target.y)
        dragMoveTo = false
        dragAtk = false
    }
}

if (canAtk && dragAtk) {
    wallCenter.body.debugBodyColor = 0x004646
    wallCenter.tint = 0x32d6ff
    killZone.body.debugBodyColor = 0xff1938
    wallDamage = true
    wallDmg()
} else {
    dragAtk = false
    wallCenter.body.debugBodyColor = 0x35e0ff
    wallCenter.tint = 0xffffff
    killZone.body.debugBodyColor = 0x35e0ff
    dragonFire.visible = false
    wallDamage = false
    wallCanShrink = false
    //console.log('no overlap')
}

// SET WALL SCALE
wallCenter.setScale(wallScale)

// WALL CAN SHRINK IF BEING DAMAGED
if (wallDamage) {
    wallShrink.paused = false 
    wallCanShrink = true
} else {
    wallShrink.paused = true 
    wallCanShrink = false
}

// DAMAGE THE WALL
if (camShake) {
    this.cameras.main.shake(shakeAmt, 0.005)
    camShake = false
    console.log('wall HP ' + wallHealth)
    console.log('wall scale ' + wallScale)
}

```

}`

I’m assuming it’s a scope issue but I’m not 100% sure. ‘isParent’ is confusing to me because I would assume I would get this error when dealing with groups. What’s odd to me is that the error doesn’t happen all the time. I’ve tried to change the order of operations - but then I randomly get undefined errors with this line `killZone.setPosition(dragonFlap.x + 120, dragonFlap.y)` Where it seems to choke on the .x or .y positioning.

For context, I am using the [https://github.com/Quinten/phaser-3-assets-as-data-uri](https://github.com/Quinten/phaser-3-assets-as-data-uri) for a single html file approach.

Any help would be greatly appreciated.

---

<div class="post-metadata">

**Author:** ![facecjf](https://yyz2.discourse-cdn.com/free1/user_avatar/phaser.discourse.group/facecjf/32/455_2.png) [@facecjf](https://phaser.discourse.group/u/facecjf)\
**Post date:** [April 16, 2019, 4:17pm UTC](https://phaser.discourse.group/t/solved-cannot-read-property-isparent-of-undefined/2119/2 "2019-04-16T16:17:29Z")

</div>

I resolved the issue by putting everything in my update function in an `if` statement

```
 function update () {
      if (startGame) {
        
      }
 }

```

Not sure as to why this is. But it’s working.