How to reproduce:
1. Open the "VegetationPainter_Crash.zip" project
2. Open the "Test_Level.unity" scene
3. Select VegetationPainter -> GroundCover in the Hierarchy
4. Click a few times in the Scene view
5. Press Play
6. If Unity didn't crash, exit Play mode and repeat steps 4-5

Actual result: Unity crashes.

Reproducible with: 2019.2.0a4, 2019.1.0b2, 2018.3.5f1, 2018.3.0a10.
Not reproducible with: 2019.2.0a11, 2019.1.0b11, 2018.3.12f1.

Notes:
Can't check 2018.1 or 2018.2 because of errors.
Errors before the crash are thrown:

Assertion failed on expression: 'm_InstanceID != InstanceID_None'
(Filename: c:\buildslave\unity\build\runtime\baseclasses\BaseObject.h Line: 377)

Failed to erase object from ms_IDToPointer. It was not part of the set.
(Filename: C:\buildslave\unity\build\Runtime/BaseClasses/BaseObject.cpp Line: 383)

Failed to erase object from ms_TypeToObjectSet. It was not part of the set
(Filename: C:\buildslave\unity\build\Runtime/BaseClasses/BaseObject.cpp Line: 386)