Steps to reproduce:
1. Open the attached project ("1198661.zip")
2. Open Animation window
3. Select GameObject in the Hierarchy
4. Press "Add Property" in the Animation window

Reproducible with: 2019.2.13f1, 2019.3.0b11, 2020.1.0a13
Not reproducible with: 2017.4.35f1, 2018.4.13f1, 2019.2.9f1, 2019.3.0b6, 2020.1.0a6

First 5 lines of the stacktrace:
0x00007FFDAC4E2B42 (mono-2.0-bdwgc) [c:\build\output\unity-technologies\mono\mono\metadata\class.c:9744] mono_field_get_type
0x00007FF6F9187ECF (Unity) scripting_field_get_type
0x00007FF6F673EFDD (Unity) UnityEngine::Animation::GetAnimatablePropertyOffset
0x00007FF6F67402FB (Unity) UnityEngine::Animation::GetGenericAnimatablePropertiesRecurse
0x00007FF6F6740398 (Unity) UnityEngine::Animation::GetGenericAnimatablePropertiesRecurse

Note:
- Crash reproduces when there's a script attached to the object being animated, containing a serialized Vector2Int or Vector3Int type variable