NullReferenceException is thrown when cancelling Tile Palette creation dialogue

How to reproduce:
1. Open the user’s attached “Iso_RotationBug” project
2. Drag the “IsometricDiamond” from the Project Browser to the Tile Palette window
3. Cancel the dialogue window

Expected result: No abnormal behaviour is observed
Actual result: “NullReferenceException: Object reference not set to an instance of an object” is thrown in the Console log

Reproducible with: 1.0.0 (2023.1.0b5, 2023.2.0a3)
Couldn’t test with: 1.0.0 (2020.3.45f1, 2021.3.18f1, 2022.2.8f1) (dragging functionality isn’t featured for Tile Palette creation)

Reproduced on: macOS 13.0 (Intel)