Load images from URL

I would use assets.loadFromUrl instead:

https://api.playcanvas.com/classes/Engine.AssetRegistry.html#loadFromUrl

Eg

// initialize code called once per entity
LoadUrlTextures.prototype.loadOnButton = function() 
{
    var self = this;
    var asset = this.app.assets.loadFromUrl(this.textureUrl, 'texture', function (error, asset) {
        if (error) {
            console.log(error);
            return;
        }
        
        var element = self.entity.element;
        element.texture = asset.resource;
    });
};