What happened:
Missing Assembly Reference exception is shown when importing the NavMeshComponents Package.

Steps to Reproduce:
1. Download and Open the Project from the link as below.
Link: https://github.com/Unity-Technologies/NavMeshComponents

Actual Result:
Unable to Run the Scene due to missing of Assembly Reference.

Expected Result:
Reference for the Assembly should be linked so as to get Scene Working.

Environment:
- Appears on both platforms (Mac and Windows).

Frequency:
- Appears Always.

Reproduces on : 2018.1.0a7, 2018.1.0a6, 2018.1.0a5
Working fine on: 2018.1.0a4, 2017.3.0f1, 2017.3.0f2