Managed DLL does not update automatically and throwing "MissingMethodException" error when accessing the code from DLL.

Steps to repro:
1. Open the attached Project.
2. Play the Main scene.
3. Press the Spacebar.

Actual Result:
"MissingMethodException: UnityEngine.Rigidbody UnityEngine.Component.get_rigidbody()BallScript.Update () (at Assets/BallScript.cs:32)" erroer thrown in console.

Expected Result:
DLL update automatically and No exception is thrown.

Reproducible in:
2019.2.0a10, 2019.1.0a4, 2019.1.0a12, 2019.1.0a11.

Working Fine in:
2019.1.0a10, 2018.3.0f2 (49866f0a5d12).

Environment:
Windows & Mac.

Stack trace:
MissingMethodException: UnityEngine.Rigidbody UnityEngine.Component.get_rigidbody()BallScript.Update () (at Assets/BallScript.cs:32)