Normal map seams

HTML

<script src="//cdn.rawgit.com/mrdoob/three.js/master/build/three.js"></script>
<script src="//cdn.rawgit.com/mrdoob/three.js/master/examples/js/controls/OrbitControls.js"></script>

CSS

body {
	  margin: 0;
}

JavaScript

let camera, scene, renderer, mesh;

init();

function init() {
  camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 0.01, 10 );
  camera.position.z = 4;
  scene = new THREE.Scene();

  new THREE.TextureLoader().load('https://i.imgur.com/KcXOMBv.png', (texture) => {
    const material = new THREE.MeshPhongMaterial({
      color: 0xffffff,
      normalMap: texture,
      shininess: 1,
      normalScale: new THREE.Vector2(1, 1),
    });

    material.onBeforeCompile = shader => {
    	shader.fragmentShader = shader.fragmentShader.replace(/}$/gm, `
      gl_FragColor = vec4(normalize(normal),1.);
      vec3 _a = gl_FragColor.xyz; 
      //_a= _a*3.-1.; //uncomment this to boost the problem
      gl_FragColor.xyz = _a;
    }`)
    }
    // Create a box geom and turn it into a sphere
    const geometry = new THREE.BoxBufferGeometry(1, 1, 1, 8, 8, 8);
    const vertices = geometry.attributes.position;
    const normals = geometry.attributes.normal;
    const radius = 1;

    for (let i = 0; i < vertices.count; i ++) {
      const v = new THREE.Vector3().fromArray(vertices.array, i * 3);
      v.normalize();
      normals.setXYZ(i, v.x, v.y, v.z);
      v.setLength(radius);
      vertices.setXYZ(i, v.x, v.y, v.z);
    }

    //vertices.needsUpdate = true;
    //normals.needsUpdate = true;

    // Assign our normals map to all sides
    mesh = new THREE.Mesh(geometry, material);
    scene.add(mesh);
    scene.add(new THREE.AxesHelper(2));

    // Add a light
    const light = new THREE.DirectionalLight(0xfffffc, 0.5);
    light.position.set(3, 3, 3);
    light.target = mesh;
    scene.add(light);

    renderer = new THREE.WebGLRenderer({ antialias: true });
    renderer.setSize(window.innerWidth, window.innerHeight);
    document.body.appendChild(renderer.domElement);

    const controls = new THREE.OrbitControls(camera, renderer.domElement);
    animate();
  });
}

function animate() {
  requestAnimationFrame(animate);
  /* mesh.rotation.y...