Investigate panic during API call with DLB

We've found a small number of instances where a request to measure the size of a repository is leading to a panic (https://new-sentry.gitlab.net/organizations/gitlab/issues/1290014/?referrer=slack&notification_uuid=1465eb87-d03a-4734-b805-3bea7072f6ba&alert_rule_id=23&alert_type=issue | https://log.gprd.gitlab.net/app/r/s/C5ml8). We need to find out the root cause for this panic and resolve it.