ImportError: cannot import name 'safe_join' from 'flask'

[mufeili]

Since 2.1.0, flask deprecates safe_join, as elaborated in its release note here. For now, a workaround is to degrade flask to an older version like pip install Flask==2.0.3. This should be fixed in the future release of GNNLens2 by either restricting Flask version or follow the latest recommended practice.

Credit to @SherylHYX for reporting the issue.