An error on no person case

[dotchang]

When I tried to use /dev/video0 as input or no person image such as dog416.png of opencv_extra, I met an error such as follows. Is it correct response?

$ python bin/demo.py dog416.png --lift_model sample/gen_epoch_500.npz --model pose_iter_440000.caffemodel --proto2d openpose_pose_coco.prototxt
MODEL: generator, N_OUT: 17, N_UNIT: 1024
[ INFO:0] Initialize OpenCL runtime...
Traceback (most recent call last):
File "bin/demo.py", line 201, in
main(args)
File "bin/demo.py", line 167, in main
points = np.float32(to36M(points, BODY_PARTS))
File "bin/demo.py", line 64, in to36M
bones[body_parts['Nose']] - thorax
TypeError: unsupported operand type(s) for -: 'NoneType' and 'float'