Steps to reproduce:

1. Create a new Unity project using the Universal 2D template
2. Open the Tile Palette window (Window > 2D > Tile Palette)
3. Dock the Tile Palette window next to the Game View
4. Create a New Tile Palette in the Tile Palette window
5. Create a new Triangle Sprite (Assets > Create > 2D > Sprite > Triangle)
6. Drag the Triangle Sprite to the Tile Palette window and save
7. Create a new tilemap from Tile Palette in the Tile Palette window
8. Enable Tile Palette Overlay in the Tile Palette window
9. Enable Tile Palette Editing in the Tile Palette Overlay
10. Enter Play Mode
11. Repeat step 8
12. Click the Triangle Sprite tile in the Tile Palette window
13. Observe the Console window

Actual results: “InvalidOperationException” and “NullReferenceException” errors are thrown

Expected results: No errors are thrown

Reproducible with versions: 6000.0.70f1, 6000.3.11f1, 6000.4.0f1, 6000.5.0a9

Tested on (OS): Ubuntu 24.04, MacOS Silicon Tahoe 26.3

Notes:

• After reproduction, the errors are thrown even without entering Play Mode