How to reproduce:
1. Open the “SkinningEditorBug_repro“ project
2. Open the “SampleScene“
3. Open the “Assets/ReproSprite“ in the Inspector Window
4. Click on the Open Sprite Editor button
5. Select the Custom Outline module
6. Select any one of the sprite rectangles
7. Click Copy
8. Make sure that no sprite rectangles are selected
9. Click on the Paste All button in the middle row

Expected result: No error is thrown
Actual result: “NullReferenceException: Object reference not set to an instance of an object“ is thrown

Reproducible with: 6000.0.11f1
Could not test with: 2021.3.40f1, 2022.3.38f1 (Cannot choose the Paste All option when no sprite rectangles are selected)

Reproducible on: macOS 14.5 (Intel), Windows 11 (User’s)
Not reproducible on: No other environments tested

Notes:
- Also the issue is reproducible with the Custom Physics Shape module
- After going through the reproduction steps once, the issue reproduces just by making sure that no sprite rectangles are selected and clicking on the Paste All button in the middle row. Once the project is closed you need to repeat the reproduction steps once again