Fix Python 3.10 compatibility and chaos driver NOGROUP handling

- Replace asyncio.TaskGroup with asyncio.gather for Python 3.10 compat
- Handle NOGROUP errors in chaos driver when workers haven't started yet

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: chrisguidry

chaos/driver.py

@@ -246,6 +246,13 @@ async def spawn_worker() -> Process:
                     "driver: Redis connection error (%s), retrying in 5s...", e
                 )
                 await asyncio.sleep(5)
+            except redis.exceptions.ResponseError as e:
+                if "NOGROUP" in str(e):
+                    # Consumer group not created yet, workers haven't started
+                    logger.debug("driver: Consumer group not yet created, waiting...")
+                    await asyncio.sleep(1)
+                else:
+                    raise
 
             # Now apply some chaos to the system:
 

tests/test_worker.py

@@ -1049,12 +1049,10 @@ async def counting_task(worker: Worker = CurrentWorker()):
             for _ in range(5)
         ]
 
-        async with asyncio.TaskGroup() as tg:
-            for w in workers:
-                await w.__aenter__()
+        for w in workers:
+            await w.__aenter__()
 
-            for w in workers:
-                tg.create_task(w.run_until_finished())
+        await asyncio.gather(*[w.run_until_finished() for w in workers])
 
         for w in workers:
             await w.__aexit__(None, None, None)