Trying to unpack the prefab casued a crash.

Version: 2018.2.0x ImprovedPrefabs. adff0ed7d03a

Steps to reproduce.
- Open the collab project BiscuitOlympics (release-qa-ftp)
- Open the Character Creation Scene.
- Select the Characters game object in the Hierarchy
- Select the Rich Tea game object.
- Drag and drop it into the character prefabs folder to create a new prefab.
- Drag and drop the new prefab backinto the Rich Tea game object. You'll be prompted that you need to unpack the object to reorder it.
- Right click the object and select unpack.
NOTICE ISSUE >> CRASH

VIDEO ATTACHED
Project files: https://tinyurl.com/y8wode5j