I get a ValueError: operands could not be broadcast together with shapes (0,) (336,) when launching the Play demo #8

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.9/tkinter/__init__.py", line 1892, in __call__
    return self.func(*args)
  File "/home/Reborn/Documents/Projects/sign_language/lsf/webcam_demo.py", line 57, in record_btn_cb
    res_txt = self.translator_manager.run_knn(feats)
  File "/home/Reborn/Documents/Projects/sign_language/lsf/modules/translator/translator_manager.py", line 100, in run_knn
    dists = np.square(self.knn_database - feats)
ValueError: operands could not be broadcast together with shapes (0,) (336,)