[Timeline] NullReferenceException thrown when clicking on an AnimationTrack in Unity

To reproduce:
1. Create a new project
2. Select Directional Light in the project
3. Click Create in Timeline Windowė
4. Save the asset
5. Click on the Animation Track in the Timeline Window

Expected Result: Track get's selected with no issues
Actual Result: NullReference Exception is thrown.

Reproduced in: 2018.1.0a4, 2018.1.0a5
Does not reproduce in: 2018.1.0a3

Repro video: https://i.imgur.com/3qwzBJd.gifv