Implement error handling and validation

[ISTIFANUS-N]

Description:
Add robust error handling, input validation, and edge case management for all smart contract functions.

[drips-wave]

This issue has been added to the Stellar Wave Program and is worth 150 Points.

🧑‍💻 Interested in contributing? Apply to work on this issue on Drips Wave, earn points, and receive rewards.

🤠 Repo maintainers: You can manage this issue's Points and Complexity on your Maintainer Dashboard here. Please keep an eye on applications and respond quickly 💙

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[vestor-dev]

@vestor-dev has applied to work on this issue as part of the Stellar Wave Program's 1st wave.

I’m ready to tackle this issues ser. With a solid background in frontend and smart contract development, I’ll deliver a clean, efficient solution that aligns with the project’s standards. I’ve already reviewed the repo and am confident I can resolve this quickly.

Let me know if you'd like me to get started!

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

[okekefrancis112]

@okekefrancis112 has applied to work on this issue as part of the Stellar Wave Program's 1st wave.

I’d like to work on this issue because it addresses a core backend concern around reliability, correctness, and scalability. I enjoy contributing to backend features that improve system behavior, data integrity, and developer experience.

I have strong experience building and maintaining backend systems using NestJS, Node.js, TypeScript, SQL/NoSQL databases, and RESTful APIs. I’ve worked on production features involving data modeling, validation, background processing, performance optimization, and debugging complex edge cases. I’m comfortable reading existing codebases, following established patterns, writing tests where appropriate, and shipping well-documented changes that integrate cleanly with frontend and infrastructure requirements.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @okekefrancis112 to this issue.

[drips-wave]

Congratulations, @vestor-dev! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on January 31, 2026.

🧑‍💻 @vestor-dev: 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.

⚠️ Important: When opening a PR, please link it to this issue to ensure it gets tracked accurately.

🤠 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.

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