mesh smoothing creates nan

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [x] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### Describe the issue

I load a triangle mesh into open3d, call `mesh.filter_smooth_taubin` and save the filtered mesh to disk. The result contains a lot of `nan` which is not expected.

### Steps to reproduce the bug

```python
import open3d as o3d

if __name__ == '__main__':
mesh = o3d.io.read_triangle_mesh('./input.ply')
out = mesh.filter_smooth_taubin(2)
o3d.io.write_triangle_mesh('./output.ply', out)
```

### Error message

_No response_

### Expected behavior

I expect no `nan` generated.

### Open3D, Python and System information

```markdown
- Operating system: Ubuntu 20.04
- Python version: 3.8.10
- Open3D version: 0.15.2
- System architecture: x86
- Is this a remote workstation?: no
- How did you install Open3D?: pip
```

### Additional information

_No response_