Reproduction steps:
1. Open the attached project "ReproProj"
2. Open the “/Assets/bake_instance_undo_bug1.unity” Scene
3. In Hierarchy, select the “Spline” GameObject
4. In Inspector, under “Spline Instantiate” Component, press the “Bake Instance“ Button
5. Press CTRL + Z
6. Observe Console

Expected result: No Errors exist
Actual result: Error “NullReferenceException: Object reference not set to an instance of an object“ is present

Reproducible with: 2.6.1 (2022.3.51f1), 2.8.0 (2022.3.61f1, 6000.0.47f1, 6000.1.0b15, 6000.2.0a9)

Testing environment: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested

Notes:
- When the NullReferenceException occurs, the component becomes invisible and stops functioning
- Another issue is that after opening “/Assets/bake_instance_undo_bug2.unity”, selecting “Spline” GameObject and under “Spline Instantiate” Component, selecting Drag_to_drop Object in “Items To Instantiate” field, a NullReferenceException occurs