🔒 Sanitize internal system errors in API responses

[mbayue]

🎯 What: Modified toErrorPayload in server/utils/errors.ts to sanitize messages for 500-level HTTP errors.
⚠️ Risk: When system errors occur (e.g. database disconnects, file IO errors), their raw .message string could contain sensitive details such as file paths, connection strings, IPs, or passwords. Exposing this information directly in API responses results in an Information Disclosure vulnerability.
🛡️ Solution: Implemented logic to check if err.status >= 500. If so, the raw error message is suppressed and replaced with a generic 'Internal Server Error' string in the response payload. 400-level status codes retain their specific messages as they are generally safe validation/client errors.

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PR created automatically by Jules for task 3638637770407784940 started by @mbayue

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Summary by cubic

Sanitizes 500-level API error messages by returning "Internal Server Error" instead of the raw message to prevent sensitive info leaks. Leaves 4xx messages unchanged and adds tests to cover both paths.

^{Written for commit fe9c036. Summary will update on new commits.}

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[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant Client
    participant API as API Route
    participant ErrorUtil as toErrorPayload
    participant System as Internal System (DB/IO)

    Client->>API: HTTP request
    API->>System: Internal operation (e.g., db.query)
    System-->>API: Error (status=500, message with sensitive info)

    alt status >= 500 (NEW: Sanitized)
        API->>ErrorUtil: toErrorPayload(error)
        Note over ErrorUtil: Replaces raw message with<br/>'Internal Server Error'
        ErrorUtil-->>API: { error: 'Internal Server Error', code, status, ... }
    else status < 500 (Unchanged: preserved message)
        API->>ErrorUtil: toErrorPayload(error)
        Note over ErrorUtil: Keeps original error.message
        ErrorUtil-->>API: { error: err.message, ... }
    end

    API-->>Client: HTTP response with sanitized payload

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_{Re-trigger cubic}