Steps:
1. Add empty GameObject to the scene
2. Make a prefab out of this GameObject
3. Delete info about GameObject in the prefab file (use OS tools for that)
4. Back to Unity Editor and double-click on the prefab asset
==>
Errors about broken prefabs are fine.
Also console has "Stage type 'UnityEditor.Experimental.SceneManagement.PrefabStage' did not clean up properly: A PreviewScene was leaked. Ensure to call 'base.CloseStage()' from your implementation of CloseStage()." error message.

Expected: The PreviewScene stage should be closed properly in case of the exception during the open prefab operation.

Please, take a look into attached movie for details.

Not repro in
Version 2018.4.9f1 (da19cd6b3373)
Version 2019.3.0b7 (82807b239940)