Fatal Error GetManagerFromContext: pointer to object of manager 'LightmapSettings' is NULL (table index 22) when closing the Editor while Generating Lighting

How to reproduce:
1. Open the attached project "Reactor.zip" and SampleScene scene;
2. In the Project folder drag Lighting Settings file located at Assets>Scenes folder to the Lighting Settings field of the Lighting window (Window>Rendering>Lighting);
3. Window > Rendering > Lighting
4. In the Lighting window click "Generate Lighting"
5. Close the Editor while the Lighting is Generating

Expected result: Editor closes
Actual result: Fatal error pops up

Reproducible with: 2020.2.0a11, 2020.3.15f2, 2021.1.16f1, 2021.2.0b6, 2022.1.0a4
Not reproducible with: 2019.4.29f1, 2020.2.0a10

Notes:
- Reproducible only when Realtime GI is enabled in the Lighting settings;
- Not reproducible when only Baked GI is enabled.