Adding a 3d model to a prefab and opening prefab asset of 3d model keeps throwing exceptions. Also, hierarchy window gets misaligned and restricts adding of new GameObjects from project window. Refer the attached video.

Steps to reproduce:
1) Create new project
2) Create an empty prefab gameObject
3) Add a 3d model as a child to this empty prefab and apply to it.
4) Right click on the 3d model > Open prefab asset

Actual result : Exceptions are thrown and no new GameObjects can be added to hierarchy from the project.
Expected result: The prefab asset opens in prefab mode.

Reproducible in: 2019.1.0a9, 2018.3.0b11, 2018.3.0b1, 2018.3.0a6

Note : Improved prefabs were introduced in 2018.3.0a6

Environment: Windows 7 and 10, Mac 10.13

Stack trace: Editor log file attached