How to reproduce:
1. Create a new project in your preferred workspace and open it
2. Connect it to Perforce
3. Submit the initial project and open the package manager
4. Install the Universal Render Pipeline package
5. Revert the package manifest.json file and immediately try to create the URP specific Pipeline Asset in the Project Window (Right-click -> Create -> Rendering -> Universal Render Pipeline -> Pipeline Asset)
6. Observe that it loses its filename, icon and a null reference exception is thrown in the console

Expected result: reverting the package manifest.json file locks the Editor until all of the packages are fully reverted preventing issues with packages that are being uninstalled (Same way the Package Manager already does it)
Actual result: reverting the package manifest.json file does not lock the Editor. This can cause issues with "half uninstalled" packages like the one described in the reproduction steps.

Reproduced in: 2020.1.0a11, 2019.3.0b9, 2019.2.10f1, 2018.4.12f1