Trouble using toonshader in three js on objects that cast a shadow - three.js

Question

I'm creating a sphere that casts and receives shadows with MeshToonMaterial but this is giving me an irregular shadow at the darkest section.
Sphere with irregular shadow:
Closer look at the sphere:
The light is:
light = new THREE.PointLight(0xffffff, 0.8, 18);
light.position.set(-3,6,-3);
light.castShadow = true;
light.shadow.camera.near = 0.1;
light.shadow.camera.far = 25;
light.shadowBias = 0.0015;
scene.add(light);
The sphere is:
mesh = new THREE.Mesh
(
new THREE.SphereBufferGeometry( 1, 32, 16 ),
new THREE.MeshToonMaterial({color:0xff4444})
);
mesh.position.y += 1;
mesh.receiveShadow = true;
mesh.castShadow = true;
mesh.position.set(-2.5, 3/2, 2.5);
scene.add(mesh);
The renderer:
renderer = new THREE.WebGLRenderer();
renderer.setSize(800,400);
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
I've tried with other models and shadow map types with similar results.
If I set:
mesh.castShadow = false;
Then what I get is:
That's pretty much the style I'm looking for, but I'm also needing it to casts shadows.
I would like to avoid using an extra sphere for casting the shadow.
How can I achieve this?

Answer 1

Disabling receiving shadows on the sphere mesh will prevent it from being rendered with the cast shadows, but it will still cast a shadow on the plane.
mesh.receiveShadow = false
However, that means that the sphere won't have any shadows cast on it from other objects, either.
Other than that, it seems like an issue with the way the toon shader handles cast shadows.