This line, assert ckpt_path in MODELS, f"Choose from {list(MODELS.keys())}"
and "e4t-diffusion-ffhq-celebahq-v1" is the only key of MODELS.
So, in function load_e4t_unet, if os.path.exists(ckpt_path) is False, you WILL get a assert error.
You should change the line 84 to ckpt_path=os.path.join(args.pretrained_model_name_or_path, "weight_offsets.pt"),
instead of ckpt_path=os.path.join(args.pretrained_model_name_or_path, "unet.pt").