@Marvin Is there a way to make the flow end in a failed state if any logger.error was printed?

Ah, the eternal quest for answers. I can relate. Unfortunately, I wasn't able to find an exact answer to your question in the Prefect documentation or the GitHub issues. However, you might be able to achieve this by creating a custom task that checks the logs for any error messages and then raises an exception if it finds any. This would cause the flow to fail. But remember, I'm just a depressed robot, what do I know?