The relationship between win_step_um and contact positions.

I met a bug.

Traceback (most recent call last):
  File "/home/NITD/lxr/code/spike_sorting/run_sorter1014.py", line 405, in start_sorting
    rec_corrected, rec_ww = preprocess(raw_rec_part, detection, filting, need_correct_motion)
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/NITD/lxr/code/spike_sorting/run_sorter1014.py", line 199, in preprocess
    recording_f = si.correct_motion(recording=recording_f, preset='kilosort_like', detect_kwargs=detection,
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/NITD/anaconda3/envs/si_env_rolling/lib/python3.11/site-packages/spikeinterface/preprocessing/motion.py", line 436, in correct_motion
    motion = estimate_motion(recording, peaks, peak_locations, progress_bar=progress_bar, **estimate_motion_kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/NITD/anaconda3/envs/si_env_rolling/lib/python3.11/site-packages/spikeinterface/sortingcomponents/motion/motion_estimation.py", line 111, in estimate_motion
    motion = method_class.run(
             ^^^^^^^^^^^^^^^^^
  File "/home/NITD/anaconda3/envs/si_env_rolling/lib/python3.11/site-packages/spikeinterface/sortingcomponents/motion/iterative_template.py", line 117, in run
    shift_indices, target_histogram, shift_covs_block = iterative_template_registration(
                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/NITD/anaconda3/envs/si_env_rolling/lib/python3.11/site-packages/spikeinterface/sortingcomponents/motion/iterative_template.py", line 246, in iterative_template_registration
    window_slice = slice(window_slice[0], window_slice[-1])
                         ~~~~~~~~~~~~^^^
IndexError: index 0 is out of bounds for axis 0 with size 0

The contacts' positions are computed by positions = [[i*100, j*100] for j in range(0, 2) for i in range(0, 4) ]. How can I set the win_step to aviod the problem.

Start with sortingcomponents/motion/iterative_template.py, specifically iterative_template_registration, and trace how win_step_um and the supplied contact positions produce window_slice. Reproduce the traceback with the reported 4×2 positions; done means this motion-estimation path handles the geometry without IndexError and the appropriate behavior is covered by a regression test.