Steps to reproduce:

1. Open any Project
2. Create a Shader Graph Asset and double click it to open it
3. Delete the Shader Graph Asset in the Project Browser, when prompted confirm to delete the Asset
4. When the "Graph removed from project" pop up prompts to recover the Asset choose "Cancel"
5. Right click the left over Shader Graph Window and choose "Close Tab"
6. When prompted to recover the Asset choose "Cancel" again

Actual results: Errors "NullReferenceException: Object reference not set to an instance of an object
UnityEditor.ShaderGraph.GraphData.GetEdges (UnityEditor.Graphing.SlotReference s, System.Collections.Generic.List`1[T] foundEdges) (at ./Library/PackageCache/com.unity.shadergraph@2132c8a97908/Editor/Data/Graphs/GraphData.cs:1311)" are logged in Console

Expected results: When choosing the option to "Close Tab" on a Shader Graph Window and the Window has been marked dirty as "(deleted)" the Shader Graph Window and Asset is discarded immediately without a prompt

Reproducible with versions: 2022.3.64f1, 6000.0.48f1, 6000.1.8f1, 6000.2.0b7, 6000.3.0a1

Tested on (OS): Windows 11