Eric stabilized frequency-based routing in the OpenTripPlanner repository by addressing a crash that occurred during itinerary construction when distanceMeters was missing. He identified that the FrequencyTransitLegBuilder required this value to prevent null pointer exceptions and implemented logic to compute and pass distanceMeters as needed. This backend development work, carried out in Java, improved the reliability of frequency-based trip construction and enhanced routing stability in production-like scenarios. Eric’s targeted debugging and code maintenance ensured more robust user experiences for frequency-based itineraries, demonstrating depth in bug fixing and a strong understanding of the system’s requirements for safe, maintainable backend code.