Exception in thread Thread-1:

[piquepq]

When I run the 02_generate_dataset.py setcover code,it didn't work,and the interpreter tells that:
Exception in thread Thread-1:
Traceback (most recent call last):
File "/home/user/anaconda3/envs/myenv/lib/python3.9/threading.py", line 973, in _bootstrap_inner
self.run()
File "/home/user/anaconda3/envs/myenv/lib/python3.9/threading.py", line 910, in run
self._target(*self._args, **self._kwargs)
File "/home/user/PycharmProjects/learn2branch/02_generate_dataset.py", line 59, in send_orders
instance = rng.choice(instances)
File "mtrand.pyx", line 915, in numpy.random.mtrand.RandomState.choice
ValueError: 'a' cannot be empty unless no samples are taken

How to fix the problem?