[Code scan] Fix CALYPSO nested atom-choice validation to avoid infinite loops

[njzjz]

Found by Codex global repository scan of deepmodeling/dpgen2 at commit 2679611a3704f5c2646c8cb353e34177518db758.

The nested name_of_atoms validation is intended to reject impossible random choices before entering the selection loop:

dpgen2/dpgen2/exploration/task/caly_task_group.py

Lines 118 to 142 in 2679611

	if isinstance(name_of_atoms, list) and all(
	[isinstance(i, list) for i in name_of_atoms]
	):
	overlap = set(name_of_atoms[0])
	for temp in name_of_atoms[1:]:
	overlap = overlap & set(temp)
	if any(map(lambda s: (set(s) - overlap) == 0, name_of_atoms)):
	raise ValueError(
	f"Any sub-list should not equal with intersection, e.g. [[A,B,C], [B,C], [C]] is not allowed."
	)
	while True:
	choice = []
	for _atoms in name_of_atoms:
	value = random.choice(_atoms)
	logging.info(
	f"randomly choose {value} from {_atoms}, already choose: {choice}"
	)
	if value in choice:
	break
	choice.append(value)
	else:
	break
	self.name_of_atoms = choice

The condition compares a set to integer 0:

(set(s) - overlap) == 0

That is always false, so invalid inputs are not rejected. For example, [["A"], ["A"]] can never produce two unique choices. The loop repeatedly chooses duplicate A, breaks the inner loop, and then restarts forever.

Suggested fix: compare against an empty set or use a direct subset check, then add a test that the impossible nested atom-choice case raises ValueError instead of hanging.