Row access uses row["sentry.dsc.root_project"] without a presence/None check, then wraps it with int(...). If Snuba returns rows where this column is missing (e.g., spans without a DSC root project tag) or where the value is None, this raises KeyError or TypeError, aborting the entire per-project volume computation for the organization. The sibling helper _get_aggregate_int was explicitly hardened in this same diff to handle None, but the group-by key was not, leaving an inconsistent safety posture.