How to reproduce:

1. Open the attached "TestFor1081094.zip" project
2. Select GameObject Prefab from the Assets folder
3. In the Inspector window click Open Prefab
4. Add a new Script Component to the Prefab
5. While the Script is being compiled leave the Prefab Edit mode and Discard Changes
6. Observe the errors in the Console window

Expected result: no errors are thrown when leaving Prefab Edit mode
Actual result: ArgumentException errors are thrown when leaving Prefab Edit mode

Reproducible with: 2018.2.0x-ImprovedPrefabs, 2018.3.0b3, 2019.1.0a2

Note: Auto Save should be disabled in the Prefab Edit mode