How to reproduce:
1. Create a new Unity project using 3D (URP) or 3D (HDRP) Template
2. Make sure that project has Visual Effect Graph package installed
3. Create a new VFX Asset using Minimal System
4. Open VFX asset
5. In Update Particles block add/create Set Age Attribute
6. Select entire Graph and delete it
7. Observe the Console window

Expected result: no errors are thrown when entire Graph is deleted
Actual result: "NullReferenceException" errors are thrown when entire Graph is deleted

Reproducible with: 17.0.0 (2023.3.0a7), 17.0.2 (2023.3.0b4)
Not reproducible with: 17.0.0 (2023.3.0a6)

Note: not reproducible with other blocks like Collision, Force, FlipBook

Error:
{code:java}
NullReferenceException: Object reference not set to an instance of an object
UnityEditor.VFX.ReadWritableAttributeProvider.GetAvailableString (UnityEditor.VFX.VFXModel model) (at ./Library/PackageCache/com.unity.visualeffectgraph/Editor/Models/Parameters/VFXAttributeParameter.cs:42)
UnityEditor.VFX.UI.StringPropertyRM+<>c__DisplayClass2_2.<FindStringProvider>b__1 () (at ./Library/PackageCache/com.unity.visualeffectgraph/Editor/GraphView/Views/Properties/StringPropertyRM.cs:84)
VFXSlotContainerEditor.DoInspectorGUI () (at ./Library/PackageCache/com.unity.visualeffectgraph/Editor/Inspector/VFXSlotContainerEditor.cs:59)
VFXSlotContainerEditor.OnInspectorGUI () (at ./Library/PackageCache/com.unity.visualeffectgraph/Editor/Inspector/VFXSlotContainerEditor.cs:315)
VFXBlockEditor.OnInspectorGUI () (at ./Library/PackageCache/com.unity.visualeffectgraph/Editor/Inspector/VFXBlockEditor.cs:23)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass74_0.<CreateInspectorElementUsingIMGUI>b__0 () (at /Users/bokken/build/output/unity/unity/Editor/Mono/UIElements/Inspector/InspectorElement.cs:729)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:219)
{code}