Worked on strengthening the Azure/azure-signalr repository by addressing a critical bug in the dependency injection path for SignalR hubs. Focused on backend development using C# and dependency injection principles, the work introduced explicit null validation for the hubName parameter in the AddHub method, ensuring that an ArgumentNullException is thrown when necessary. This change prevents potential runtime errors and improves the robustness of the DependencyInjectionExtensions. To guarantee reliability and prevent regressions, comprehensive unit tests were added, specifically targeting the new validation logic. The approach emphasized defensive programming and thorough testing, contributing to a more stable and maintainable codebase.