CloudWatch Logs StartQuery API fails with TypeError when called from Grafana

When Grafana or other clients invoke the CloudWatch Logs StartQuery API against LocalStack, the request fails with HTTP 500 InternalError. The underlying cause is a TypeError in the moto library backend where it attempts to iterate over None when log_group_names is not properly passed. Basic log operations like get-log-events continue to work normally.

Use awslocal logs get-log-events as a workaround for direct log retrieval. Monitor LocalStack logs for 'TypeError: NoneType object is not iterable' errors in moto/logs/models.py. Upgrade LocalStack to a version beyond 4.0.4.dev135 where this issue was resolved. For Grafana integration, consider alternative log data sources until the issue is fixed.