ValueError: 'a' cannot be empty unless no samples are taken

Excellent work!
Encountered the following error, how to solve ah? Thank you for your reply.

Traceback (most recent call last):
File "train.py", line 64, in
train(args)
File "train.py", line 57, in train
ppo_runner, train_cfg = task_registry.make_wmp_runner(env=env, name=args.task, args=args, train_cfg=train_cfg)
File "/home/WMP-master/legged_gym/utils/task_registry.py", line 207, in make_wmp_runner
runner = WMPRunner(env, train_cfg_dict, log_dir, device=args.rl_device)
File "/home/WMP-master/rsl_rl/runners/wmp_runner.py", line 108, in __init__
amp_data = AMPLoader(
File "/home/WMP-master/rsl_rl/datasets/motion_loader.py", line 145, in __init__
traj_idxs = self.weighted_traj_idx_sample_batch(num_preload_transitions)
File "/home/WMP-master/rsl_rl/datasets/motion_loader.py", line 193, in weighted_traj_idx_sample_batch
return np.random.choice(
File "mtrand.pyx", line 915, in numpy.random.mtrand.RandomState.choice
ValueError: 'a' cannot be empty unless no samples are taken