2d Animation Package sample project throws Assertion failed errors on importing. Refer the attached screenshot

Steps to reproduce:
1) Create a new project
2) Window > Package Manager
3) Install 2D Animation
4) Import sample project

Actual result: Assertion failed errors spam the console

Expected result: No errors appear in console on importing the project

Occurring on: 2020.1.0a12, 2020.1.0a1

Not Reproducible on: 2019.2.0b10

Environment: Only on Windows

Stack trace:

1) Assertion failed on expression: 'IsScalar()'
2) Tried to get a scalar value from a mapping node