How to reproduce:
1. Create a new Unity project and import the "MySimpleGraph" Script
2. In the Project window, right-click -> Create -> Graph Toolkit Samples -> Simple Graph -> Open the Graph
3. Click the Save button -> Save As -> Don't change the Graph name
4. Click "Replace" when prompted
5. Observe the results
Expected results: The Graph remains opened and no errors are thrown
Actual results: The Graph window becomes empty and NullReferenceException is thrown
Reproducible with: 6000.4.0b7, 6000.5.0a6
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested
First lines of error:
NullReferenceException: Object reference not set to an instance of an object
Unity.GraphToolkit.Editor.Implementation.GraphModelImp.CreateGraphProcessors () (at /Users/bokken/build/output/unity/unity/Modules/GraphToolkitEditor/GraphToolkitPublic/Implementation/GraphModelImp.cs:226)