Python asyncio task group error handling patterns

When using Python asyncio TaskGroup, exceptions from child tasks need special handling. If one task fails, the others are cancelled by default which may not be desired.

Use ExceptionGroup handling with try/except* syntax. For individual task errors, wrap each task coroutine in a try/except. Can also use return_exceptions=True with asyncio.gather for backward compat.

TaskGroup uses structured concurrency — when one child fails, the group cancels remaining children and raises ExceptionGroup. This is intentional but catches many developers off guard.