Reorderable Lists in the Editor do not work, instead throwing an error message.

Reproduction Steps:
1. Open the attached project
2. Open the Player Settings
3. In Splash Image, attempt to change the order of the Logos by dragging them

Expected Result:
The list items can be reordered.

Actual Result:
NullReferenceException: Object reference not set to an instance of an object

Note that this issue also occurs for other lists such as the Grapics API (Windows, Mac & Linux) and Color Gamut For Mac. It does not, however, happen with lists like the Virtual Reality SDKs.

Reproducible in versions 2019.2.0a12, 2019.2.0b1, 2019.3.0a2.
Not reproducible in versions 2019.2.0a11, 2019.1.2f1.