Reproduction steps:
1. Open user attached project
2. Select "Assets\Prefabs\Cards\Ping.prefab"
3. Edit the Card Flipper Script by renaming any of the Sprite variables
4. Go back to Unity

Expected result: The Sprite variable is edited
Actual result: The Editor crashes

Reproducible with: 2020.2.0a18, 2020.2.2f1, 2021.1.0b3, 2021.2.0a2
Not reproducible with: 2019.4.18f1
Could not test with: 2018.4.30f1 (Prefab breaks)

Notes:
On a clean project the Script Component disappears from the Inspector until the Prefab is reselected instead of crashing