Worked on the better-auth/better-auth repository to address a critical issue in session management during API error scenarios. Focused on preserving Set-Cookie headers when API errors are thrown, ensuring that user sessions remain intact even when authentication failures occur. Utilized TypeScript to implement robust error handling and thorough testing, maintaining the integrity of authentication flows. The solution involved modifying the API response logic so that cookie-related headers are not lost during error responses, reducing user login friction and improving session continuity. This targeted bug fix enhanced the reliability of session management and contributed to a smoother authentication experience for users.