Steps to reproduce:
1. Create a new HDRP project
2. In the Project window create any shader (right-click > Create > Shader Graph > Lit Shader Graph)
3. Open the "Create Node" menu > Expression
4. In Expression Node expand the Preview window
5. In the text field type “lerp (x, y, t)”
6. Press Undo shortcut two times (Command+z)
7. Try to collapse Preview window
Actual results: The Preview window can’t be collapsed, the toggle is unresponsive and the Preview remains permanently expanded
Expected results: The Preview window should collapse normally regardless of whether the expression entered is valid, incomplete, or malformed. UI controls on a node should always remain fully functional and independent of the node's compilation or evaluation state
Reproducible with versions: 6000.5.0b11, 6000.6.0a6
Can’t test with versions: 6000.4.10f1, 6000.3.17f1 and lower (Expression Node is not available)
Tested on (OS): macOS Tahoe 26.4.1 (M1), Ubuntu 24.04