Remove exit() from select_checkpoint()

def select_checkpoint():

    """Raises `FileNotFoundError` if no checkpoints are found."""

    model_checkpoint = shared.opts.sd_model_checkpoint

    checkpoint_info = checkpoint_alisases.get(model_checkpoint, None)

        return checkpoint_info

    if len(checkpoints_list) == 0:

        print("No checkpoints found. When searching for checkpoints, looked at:", file=sys.stderr)

        error_message = "No checkpoints found. When searching for checkpoints, looked at:"

        if shared.cmd_opts.ckpt is not None:

            print(f" - file {os.path.abspath(shared.cmd_opts.ckpt)}", file=sys.stderr)

        print(f" - directory {model_path}", file=sys.stderr)

            error_message += f"\n - file {os.path.abspath(shared.cmd_opts.ckpt)}"

        error_message += f"\n - directory {model_path}"

        if shared.cmd_opts.ckpt_dir is not None:

            print(f" - directory {os.path.abspath(shared.cmd_opts.ckpt_dir)}", file=sys.stderr)

        print("Can't run without a checkpoint. Find and place a .ckpt or .safetensors file into any of those locations. The program will exit.", file=sys.stderr)

        exit(1)

            error_message += f"\n - directory {os.path.abspath(shared.cmd_opts.ckpt_dir)}"

        error_message += "Can't run without a checkpoint. Find and place a .ckpt or .safetensors file into any of those locations."

        raise FileNotFoundError(error_message)

    checkpoint_info = next(iter(checkpoints_list.values()))

    if model_checkpoint is not None: