How to reproduce:
1. Open the user's attached project
2. Open scene Scenes/SampleScene
3. Open the Tile Palette through Window -> 2D -> Tile Palette
4. Dock the Tile Palette window tab to the Editor so that it stays visible
5. Go to the Scene view
6. In the Hierarchy window, double-click the GameObject "Tilemap" (under "Grid")
7. Observe the tilemap in the Scene view
8. Press the Play button
9. Go to the Scene view again
10. Press the Play button again to stop playing

Expected result: tilemap stays visible in the Scene view
Actual result: tilemap disappears from the Scene view, errors are thrown in the Console

Reproducible with: 2021.1.20f1, 2021.2.0b8
Not reproducible with: 2021.2.0b9, 2021.2.0b11, 2022.1.0a7
Could not test with: 2019.4.30f1, 2020.3.17f1 (cannot resolve errors after downgrading the user's project)

Notes: tile icon sprites appear incorrectly in some instances