Meshes going black after calling geometry.computeVertexNormals()

Questions
1

Hi, I was trying to add shadows, and when I tried the following solution some of the meshes in the model changed to black color. I didn’t understand what’s wrong.

My code:

let loader = new THREE.GLTFLoader();
      loader.parse(text, undefined,
        function (gltf) {
          model = gltf.scene;
          model.scale.set(1, 1, 1);
          scene.add(model);
          model.traverse((mesh) => {
            if (!mesh.isMesh) return;
            mesh.material.roughness = 0;
            mesh.material.metalness = .5;
            mesh.castShadow  = true
            mesh.recieveShadow = true
            mesh.geometry.computeVertexNormals()
          });
        },
        undefined,
        function (error) {
          buttonBussy(false);
          console.error(error);
        }
      );

Thanks,
Binoy