How to reproduce:
1. Create and open a new project
2. In the Hierarchy, create a new empty GameObject
3. Select the newly created object, add a Sprite Renderer component
4. In the menu bar, navigate to Window > Animation > Animation
5. Create a new Animation Clip
6. Add at least one Transform and Sprite Renderers: Sprite property
7. Drag select all keyframes
8. Right click to open contextual menu
9. Observe the Console and Animation window

Actual result: Errors are thrown in the Console and contextual menu does not open
Expected result: No errors are thrown and contextual menu opens up normally

Reproducible with: 6000.2.0a9, 6000.3.16f1, 6000.4.7f1, 6000.5.0b8, 6000.6.0a5
Not reproducible with: 6000.0.75f1, 6000.2.0a8 (6bc6fbc26ac6)

Reproducible on: macOS 26.4 (M1 Pro), Windows 11 (user reported)
Not reproducible on: No other environment tested

Note:
Errors thrown:
- “GUI Error: Invalid GUILayout state in AnimationWindow view. Verify that all layout Begin/End calls match”
- “NullReferenceException: Object reference not set to an instance of an object”