The source of this bug reported by QA was the use case when the parent of a nested URL alias was gone due to data corruption, the command displayed error referring to itself. It was fixed by moving cleanup prior to regenerating aliases, which was rather a workaround.

URLAliasService::refreshSystemUrlAliasesForLocation API should attempt to self-correct entries for which Repository contains all informations to perform such cleanup. Removing corrupted entries should be the last step if data is corrupted beyond recovery.