i wanna to know something about generate ligand

[1106280506Hx]

"I would like to know, when sampling to generate ligand molecules, isn't it enough to just provide the pdb file of the receptor molecule? Why does the dataset in generate.config also include ligand molecule data, and when I tried to use only the receptor, it failed."

Traceback (most recent call last):
  File "/home/huangxiao/SBDD/LiGAN/generate.py", line 48, in <module>
    main(sys.argv[1:])
  File "/home/huangxiao/SBDD/LiGAN/generate.py", line 43, in main
    generator.generate(**config['generate'])
  File "/home/huangxiao/SBDD/LiGAN/ligan/generating.py", line 302, in generate
    ) = self.forward(
  File "/home/huangxiao/SBDD/LiGAN/ligan/generating.py", line 191, in forward
    = data.forward(interpolate=interpolate, spherical=spherical)[:5]
  File "/home/huangxiao/SBDD/LiGAN/ligan/data.py", line 287, in forward
    input_rec_coord_set, input_lig_coord_set = ex.coord_sets
ValueError: not enough values to unpack (expected 2, got 1)

this is the result that i try only using recptor