Iterating through asset cards fails when unrelated asset is broken

**Describe the bug:** Getting `AssetCardErrors` when iterating through a hub with `hub.iter_cards()` when unrelated assets are incomplete/incorrect. Complete error: ``` File "/storage/home/gilkeren/code/omnilingual/.venv/lib/python3.12/site-packages/fairseq2/assets/store.py", line 126, in _do_retrieve_card raise AssetCardError(leaf_name, msg) fairseq2.assets.card.AssetCardError: ... base asset of the ... asset card does not exist. ```