How to reproduce:
1. Open attached project "Island_Defenders_stripped.zip" and scene "Game"
2. In Hierarchy window, select "Terrain" object
3. In Inspector window, "Nav Mesh Surface" -> press "Bake" multiple(5) times (or modify the surface settings so it takes longer to bake, need time for the following step)
4. While "Nav Mesh Surface" is baking, constantly resize any window (a lot of warnings should appear in the Console window)
5. After the baking process is complete, continue to resize the window for a few seconds
6. Try baking the nav mesh surface (optional step, the Bake process is stuck at 0%)
7. Close Unity (if unable to reproduce this bug, repeat from step 1 to step 5)

Expected result: Unity closes
Actual result: Unity freezes, Task Manager is needed to close the Editor

Reproducible with: 2019.1.0a12, 2019.1.10f1, 2019.2.0b9, 2019.3.0a9
Not reproducible with: 2017.4.30f1, 2018.4.4f1, 2019.1.0a11

Additional notes:

• When the Library folder is corrupted a lot more warnings are thrown on the 2018.4.4f1 Unity versions (compared to when the Library folder on launch is deleted)