Object picker for Graph Toolkit Variables displays assets that can lead to InvalidCastException and FocusController has unprocessed focus events warning being thrown

Steps to reproduce:

1. Open the attached project
2. Open the typeTest.txmkr graph asset
3. Try dragging the "New Terrain" Asset from the Project Window to the testTerrain_1 port value in the UniformNode
4. Observe that assigning the Asset reference by drag and drop does not work
5. Click the Object Picker icon for the testTerrain_1 port value
6. Observe that "New Terrain" Asset is listed as an option
7. Double-click on the "New Terrain" Asset to pick the object
8. Observe the Console window

Actual results: InvalidCastException: Specified cast is not valid error is thrown that points to the GTK Module. "FocusController has unprocessed focus events. Clearing." warning is also thrown

Expected results: Object Picker does not display incompatible Type assets or fails gracefully, either through UI (Inspector window shows "Type mismatch" in the value field when performing an identical operation - image attached) or with a clean Error message indicating user error

Reproducible with versions: 6000.4.0b7, 6000.5.0a6

Can’t test with versions: 6000.0.67f1, 6000.3.7f1 (Graph Toolkit not available as a built-in module)

Tested on (OS): macOS 26.2, Windows 11