I ran into this while testing org access management: when creating a group with an existing slug, the UI showed a generic “Something went wrong” toast. That made it unclear what to fix, especially compared to sub-organization create/update, which already returns a clear duplicate-slug message.
This change improves UX by returning a specific error for duplicate group slugs, so users immediately know what went wrong and how to resolve it.
The scope is intentionally minimal and easy to review:
• small backend-only update in
group-service.ts
• no API contract changes
• no frontend changes required
• behavior is aligned with existing sub-org error handling pattern