When the attached project is upgraded to 2019.3. There are 2 errors thrown (details can be found below)

To reproduce
- Download and open the attached project (https://drive.google.com/file/d/1F7HqnPDWz28KeEV2VSZCk2MZfyLoNZ8L/view?usp=sharing)
- Upgrade to 2019.3.0b1 or above
- Open the console log (Window ->General->Console log)

Expected result:
The project should open with no errors

Actual result:
2 rigidbody errors come up in the console

Workaround
Close and reopen the same project

Platform:
Tested on Windows + MAC

Tested in in 2019.3.0b8, 2019.3.0a11, 2019.3.0b1, 2017.4.30f1, 2019.8.1.0b6,2018.4.5f1
Reproducible in 2019.3.0b8, 2019.3.0a11, 2019.3.0b1
Working as expected in: 2017.4.30f1, 2018.4.5f1

Errors thrown:

The type name "Rigidbody "can not be found in the namespace "UnityEnguine" - error CS1069
The type name "Rigidbody "can not be found in the namespace "UnityEnguine" - error CS1069