Add typed SdkErrorCode enum and SdkError class to errors.ts

[Kingsman-99]

Description

src/errors.ts throws plain Error objects with string messages. Consumers cannot reliably switch on error types — they must string-match the message, which breaks when wording changes. This issue adds a typed SdkErrorCode enum and an SdkError class that carries it.

Acceptance Criteria

• SdkErrorCode enum exported from src/errors.ts with at minimum: INVOICE_NOT_FOUND, INSUFFICIENT_FUNDS, DEADLINE_EXPIRED, INVALID_RECIPIENT, CONTRACT_REJECTED, NETWORK_TIMEOUT, RATE_LIMITED
• SdkError extends Error with code: SdkErrorCode and details?: unknown fields
• All existing throw new Error(...) calls in src/errors.ts replaced with throw new SdkError(...)
• isSdkError(e: unknown): e is SdkError type guard exported
• SdkError and SdkErrorCode exported from src/index.ts
• Unit tests: isSdkError returns true/false correctly, SdkError carries correct code, existing string messages preserved in .message

Context

• Target file: src/errors.ts and src/index.ts
• Do not change the .message string content of any existing error — only add the code field

[Peculiarr7]

Hi! I came across this issue and would love to work on it. I have experience with similar tasks and I'm confident I can investigate, implement a clean solution, and thoroughly test it before submitting a PR. If the issue is still open, I would appreciate it if you could assign it to me. I’ll prioritize this immediately and ensure a reliable solution is delivered as soon as possible. Thank you!

[bobo-24]

Hi! I’m a full-stack developer with a strong blockchain background, and I’m confident I can resolve this issue quickly and effectively. I’ll deliver a clean, reliable solution with immediate attention to detail, ensuring it’s completed as soon as possible. Please assign it to me—I’m ready to get started right away.

[rasputin2525]

Hey team, I'd like to take this one on!

I can implement the typed error hierarchy in src/errors.ts:

Export the SdkErrorCode enum containing all required error codes (INVOICE_NOT_FOUND, INSUFFICIENT_FUNDS, DEADLINE_EXPIRED, etc.).

Implement and export the SdkError class (extending Error with code: SdkErrorCode and details?: unknown) while preserving all existing string message contents.

Export the isSdkError(e: unknown): e is SdkError type guard and re-export SdkError & SdkErrorCode from src/index.ts.

Refactor existing throw new Error(...) calls to throw SdkError instances.

Add unit tests to verify isSdkError type guarding, error code assignments, and preserved message strings.

Could you please assign issue #607 to me? Thanks!

[grantfox-oss]

🦊 GrantFox — @rasputin2525 has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #607)
2. Your PR will be reviewed by the Stellar-split maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@rasputin2525's PR #632 was approved and merged by @Kingsman-99.

🏆 @rasputin2525: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (239 total points). Track your full progress on GrantFox.

👏 Great work, @rasputin2525! Keep contributing to Stellar-split.