If the timeline window with several tracks that contain open inline curves is resized vertically as small as it can go and then sized up again, an ArgumentException will appear in the console:

ArgumentException: Getting control 4's position in a group with only 4 controls when doing Repaint
Aborting

1. Open Attached project and load timeline.scene
2. Select TimelineContainer from the scene Hierarchy
3. Open the inline curves of the clips on the tracks
4. Resize the Timeline Window to be as small vertically as possible
5. Size the Timeline window up again
6. Exception occurs