I'm having an issue with a collision handler I made:

var PlayScene = cc.Scene.extend({
    // Some variables
    initPhysics: function () {
       this.space = new cp.Space();
       this.space.addCollisionHandler(spriteTag.player, spriteTag.rocketSprite, this.onCollisionRocketPickup.bind(this), null, null, null);
    },
    ...
    onCollisionRocketPickup: function (arbiter, space) {
        // Call methods from other layers
        this.getChildByTag(tagOfLayer.animation).addRocketPickedUp();
        this.getChildByTag(tagOfLayer.topLayer).addShootButtonRocket();
    },
    ...
});

When the player hits a rocketSprite (physicsSprite) it creates/logs this error and the methods from other layers are not run:

jsb: ERROR: File /Users/jenkins/Work/CocosPackageAuto/CocosFramework/cocos2d-x/cocos/scripting/js-bindings/auto/jsb_cocos2dx_auto.cpp: Line: 1479, Function: js_cocos2dx_Node_addChild
Invalid Native Object
jsb: ERROR: File /Users/jenkins/Work/CocosPackageAuto/CocosFramework/cocos2d-x/cocos/scripting/js-bindings/manual/chipmunk/js_bindings_chipmunk_manual.cpp: Line: 815, Function: myCollisionBegin
Error calling collision callback: begin​

​I am using Cocos2d-x v3.7 (JavaScript) on a Mac running on Xcode.
Any help would be much appreciated.