On creating 'State' and 'Script' Graph when 'Show Data..' option is selected then NullReferenceException thrown in console. Refer attached video and stack trace.

Steps to repro:
1. Create a new Project
2. Project window > Create > Visual Scripting > 'State' and 'Script' Graph
3. Inspector > Edit Graph > 'Show Data..' option > Click

Actual Result:
Error is thrown on selecting 'Show Data..' option in 'State' and 'Script' Graph.

Expected Result:
On selecting 'Show Data..' option respective Data should show without throwing any error.

Reproducible on:
2021.1.0b1 with Version 1.5.1-pre.3

Note: Visual Scripting has been introduced in 2021.1.0b1

Environment: Windows 10 and Mac 10.15

Stack Trace:
NullReferenceException: Object reference not set to an instance of an object
Unity.VisualScripting.SerializationData.ToString (System.String title) (at Library/PackageCache/com.unity.visualscripting@1.5.1-pre.3/Runtime/VisualScripting.Core/Serialization/SerializationData.cs:67)
Unity.VisualScripting.SerializationData.ShowString (System.String title) (at Library/PackageCache/com.unity.visualscripting@1.5.1-pre.3/Runtime/VisualScripting.Core/Serialization/SerializationData.cs:110)
Unity.VisualScripting.LudiqEditorWindow.<AddItemsToMenu>b__11_0 () (at Library/PackageCache/com.unity.visualscripting@1.5.1-pre.3/Editor/VisualScripting.Core/Windows/LudiqEditorWindow.cs:89)
UnityEditor.GenericMenu.CatchMenu (System.Object userData, System.String[] options, System.Int32 selected) (at /Users/bokken/buildslave/unity/build/Editor/Mono/GUI/GenericMenu.cs:126)