fix infinite loop

Author: sanderegg

packages/service-library/src/servicelib/logging_errors.py

@@ -31,7 +31,9 @@ def create_troubleshootting_log_message(
     def _collect_causes(exc: BaseException) -> str:
         causes = []
         current = exc.__cause__
-        while current is not None:
+        seen = set()  # Prevent infinite loops
+        while current is not None and id(current) not in seen:
+            seen.add(id(current))
             causes.append(f"[{type(current).__name__}]'{current}'")
             current = getattr(current, "__cause__", None)
         return " <- ".join(causes)

packages/service-library/tests/test_background_task.py

@@ -207,12 +207,16 @@ async def _func() -> None:
     assert mock_func.call_count > 1
 
 
+class CustomError(Exception):
+    pass
+
+
 async def test_periodic_task_logs_error(
     mock_background_task: mock.AsyncMock,
     task_interval: datetime.timedelta,
     caplog: pytest.LogCaptureFixture,
 ):
-    mock_background_task.side_effect = RuntimeError("Test error")
+    mock_background_task.side_effect = CustomError("Test error")
 
     with caplog.at_level(logging.ERROR):
         async with periodic_task(