THREE.js - Can someone explain why my page only opens OBJ file and MTL file don't upload?

Question

My problem is about the loading of the .MTL file in the script. It opens nice my OBJ file but the .MTL file doesn´t upload in the page, it only shows in grey or black. You can see the files in this link if you want to try: OBJ: https://github.com/carva28/ntc25anos/blob/testing/models/cat.obj MTL: https://github.com/carva28/ntc25anos/blob/testing/models/cat.mtl

My THREE version is 97

function init() {
    var scene = new THREE.Scene();
    var camera = new THREE.PerspectiveCamera(5, window.innerWidth / window.innerHeight, 0.5, 1000);
    var webGLRenderer = new THREE.WebGLRenderer();
    webGLRenderer.setClearColor(new THREE.Color(0xfabbff));
    webGLRenderer.setSize(window.innerWidth, window.innerHeight);
    webGLRenderer.shadowMap.enabled = true;
    camera.position.x = 0.5;
    camera.position.y = 10;
    camera.position.z = 60;
    camera.lookAt(new THREE.Vector3(0, 0, 0));
    var spotLight = new THREE.SpotLight(0xffffff);
    spotLight.position.set(0, 40, 30);
    spotLight.intensity = 2.5;
    scene.add(spotLight);
    document.getElementById("WebGL-output").appendChild(webGLRenderer.domElement);
    var step = 0;
    var mesh;
   var mtlLoader = new THREE.MTLLoader();
    mtlLoader.setPath("models/");
    mtlLoader.load('cat.mtl', function(materials) {
        materials.preload();
        var objLoader = new THREE.OBJLoader();
        objLoader.setMaterials(materials);
        objLoader.setPath("models/");
        objLoader.load('cat.obj', function(object) {
          object.scale.set(1, 1, 1);
          mesh = object;
          scene.add(mesh);
          object.rotation.x = 0;
          object.rotation.y = -1.3;
        });
    });

    render();