I am making a simple particle system with the mind that garbage collection shouldn't be a big issue, so i didn't bother to use Pool.

 if (ghost.nextParticle < fixedGameTime) {
      /* #IfDev */
      // console.log(`ghostParticles`);
      /* #EndIfDev */
      ghostParticles.addChild(Sprite({
          x: ghost.x,
          y: ghost.y,
          color: '#000000',
          radius: Math.random() * 3 + 1,
          fadeRate: Math.random() * 0.05,

          update() {
              this.y -= 0.5;
              this.opacity -= this.fadeRate;

              if (this.opacity < 0) ghostParticles.removeChild(this);
          },
      }));


      ghost.nextParticle += (Math.random() * 50) + 20;
  }

However, removeChild isn't sufficient to remove references,
setting this._uf to null helps, but there are still other lingering references.

So i opened the profiler:

turns out the init callback still remembers the sprite, as written in https://github.com/straker/kontra/blob/main/src/gameObject.js#L270-L272

this on('init', ()=>...) registers an anonymous callback, so i have no ways to off() it either.

To solve the issue, there are 2 folds:

(1) To just address the issue i am having, it would be nice if we have a clearCallbacks('init') to call, or off('init') without a callback can just delete all callbacks associated to this key (wait isn't that going to wipe callbacks if the user calls off('init', callback) with a null-callback? I dunno, clearCallbacks() may increase the package size tho, or does it not?)

(2) Is to just fix the GameObject destroy code, to properly clear the callback, probably adding 1 more named function so that it can call off() properly.

Quote slack message:

Oh really? so you are saying it is probably a bug that init did not get cleared?