ValueError: min() arg is an empty sequence

[wsyzy]

I've sliced over 4000 stl models with this tool, and all of them have been sliced successfully except for 5 models that failed to slice, and I've confirmed that the 5 models themselves are fine. These 5 models report the following errors：

`multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
File "/home/ubuntuuser/anaconda3/lib/python3.10/multiprocessing/pool.py", line 125, in worker
result = (True, func(*args, **kwds))
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/slice.py", line 54, in paint_z_plane
perimeter.lines_to_voxels(lines, pixels)
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/perimeter.py", line 10, in lines_to_voxels
paint_y_axis(lines, pixels, x)
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/perimeter.py", line 40, in paint_y_axis
min_idx = -min((x, -i) for i, x in enumerate(distances))[1]
ValueError: min() arg is an empty sequence
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/home/ubuntuuser/anaconda3/bin/stltovoxel", line 8, in
sys.exit(main())
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/main.py", line 46, in main
convert_files(args.input, args.output, color_tuples, args.resolution, args.voxel_size, args.pad, args.parallel)
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/convert.py", line 41, in convert_files
vol, scale, shift = convert_meshes(meshes, resolution, voxel_size, parallel)
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/convert.py", line 23, in convert_meshes
cur_vol = slice.mesh_to_plane(org_mesh, shape, parallel)
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/slice.py", line 37, in mesh_to_plane
results = [r.get() for r in result_ids]
File "/home/ubuntuuser/anaconda3/lib/python3.10/site-packages/stltovoxel/slice.py", line 37, in
results = [r.get() for r in result_ids]
File "/home/ubuntuuser/anaconda3/lib/python3.10/multiprocessing/pool.py", line 774, in get
raise self._value
ValueError: min() arg is an empty sequence
`

[cpederkoff]

Hi @wsyzy can you try this again with the new version of the code? I encountered a similar error while writing #62 and think that it may now be fixed.
Thanks,
Christian