Bone error when replacing a model

Hi all i have a character which works perfectly i used mixamo for the animations and when i try to replace the model i get this FBXLoader.js:107 TypeError: Cannot read properties of undefined (reading 'bones')

Now the only thing that i can see that actually changes with the fbx is now instead of the bones just saying what they are like “Head” like in the old mixamo files now more recently they all start with “mixamorig:” so “mixamorig:Head” etc i can rename all these and the vertex groups back to normal but this doesn’t solve the issue either am i missing something to why newer mixamo models won’t work with my old code? here is the code loading the bones:

  _LoadModels() {
      const loader = new FBXLoader();
      loader.load('boy.fbx', (fbx) => {
        this._target = fbx;
        this._params.scene.add(this._target); = 'player';
        this._bones = {};
 this._target.position.y = 0;
        for (let b of this._target.children[1].skeleton.bones) {
          this._bones[] = b;

        this._target.traverse(c => {
          c.castShadow = true;
          c.receiveShadow = false;


          if (c.material && {
   = THREE.sRGBEncoding;

            topic: 'load.character',
            model: this._target,
            bones: this._bones,

        this._mixer = new THREE.AnimationMixer(this._target);

        const _OnLoad = (animName, anim) => {
          const clip = anim.animations[0];
          const action = this._mixer.clipAction(clip);
          this._animations[animName] = {
            clip: clip,
            action: action,

        this._manager = new THREE.LoadingManager();
        this._manager.onLoad = () => {
          window.sta = this._stateMachine;
        const loader = new FBXLoader(this._manager);
        loader.load('Sword And Shield Idle.fbx', (a) => { _OnLoad('idle', a);  gameLook = true;});
        loader.load('Sword And Shield Run.fbx', (a) => { _OnLoad('run', a); });
        loader.load('Sword And Shield Walk.fbx', (a) => { _OnLoad('walk', a); });
        loader.load('Sword And Shield Slash.fbx', (a) => { _OnLoad('attack', a); });
        loader.load('Sword And Shield Death.fbx', (a) => { _OnLoad('death', a); });
        loader.load('Sword And Shield Kick.fbx', (a) => { _OnLoad('charge', a); 

here is the full code:

here are all the animations and the model or the old and new one i am trying to add: (5.8 MB) (3.9 MB)

can any spot what im missing or doing wrong?