Robust Error Handling and Socket Cleanup in Asyncio Server Connections

In asynchronous network programming, properly handling errors and cleaning up resources like sockets is crucial to prevent resource leaks and ensure system stability. When an error occurs during the acceptance of a new connection—such as during protocol or transport creation—it's important to close the socket immediately and report the error appropriately. This prevents silent failures and resource exhaustion, which can degrade server performance or cause crashes over time.

This PR modifies the `BaseSelectorEventLoop._accept_connection2()` method to close the accepted socket if either the `protocol_factory()` or transport creation raises an exception. Previously, the socket would remain open until garbage collection, causing a resource leak. The fix also ensures that errors are reported via the event loop's exception handler regardless of debug mode when the failure happens during acceptance. However, once the transport is established, error reporting remains debug-only to avoid noisy logs from common issues like SSL handshake failures. The PR includes new tests that fail without this fix and pass with it, confirming the socket cleanup and error reporting improvements.

Understanding and implementing proper error handling and resource cleanup prevents subtle bugs like socket leaks that can degrade server reliability and performance over time. This ensures your asynchronous servers remain robust under load and unexpected conditions, improving maintainability and user experience.

Review the changes in `_accept_connection2()` that handle exceptions during connection acceptance. How would you extend this pattern to handle errors during other asynchronous operations in your server, such as during data transmission or connection closing? Sketch a strategy to ensure resources are always cleaned up and errors reported appropriately in those contexts.