[Backend] Add structured error responses (map Soroban failures)

[mimijuwonlo-commits]

Goal

Return actionable errors to the frontend (e.g., contract error codes) instead of generic 500.

Acceptance criteria

• Consistent { error, message, details? } schema.
• Includes Soroban SplitError mapping where possible.

[Robinsonchiziterem]

@Robinsonchiziterem has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I'm a backend developer with experience designing consistent and developer-friendly error handling systems. I've implemented structured error response schemas with clear fields like error, message, and details, and I’m comfortable mapping domain-specific errors (such as Soroban contract failures) into actionable responses for the frontend. I would love to work on this issue, my ETA is 1 hour.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Robinsonchiziterem to this issue.

[drips-wave]

Congratulations, @Robinsonchiziterem! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @Robinsonchiziterem: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[drips-wave]

This issue has been marked as completed by a Drips Wave moderator for @Robinsonchiziterem as part of the Stellar Wave Program's 3rd Wave 🥳

Moderator's reason: [Auto-assessed] PR #79 was merged and directly addresses the issue requirements by implementing structured error responses and mapping Soroban contract errors to specific status codes and messages. Although the issue remains open, the merged PR confirms the work was accepted by the maintainers.

😎 @Robinsonchiziterem: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.

ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.