How to reproduce:
1. Open the “NodeIssue.zip” project
2. Open “New Shader Graph” (Assets > New Shader Graph)
3. Click on the “Mask” field
4. Click outside of “Swizzle” Node and observe the Console window

Expected result: No errors
Actual result: “NullReferenceException” and “Assertion failed” errors appear also the cursor is stuck into a drag select state

Reproducible with: 10.10.0 (2020.3.37f1), 12.1.7 (2021.3.7f1), 13.1.8 (2022.1.12f1), 14.0.3 (2022.2.0b3), 15.0.0 (2023.1.0a4)

Reproduced on: macOS 12.4 (Intel)

Error:
NullReferenceException: Object reference not set to an instance of an object

UnityEditor.ShaderGraph.SwizzleNode.set_maskInput (System.String value) (at Library/PackageCache/com.unity.shadergraph@15.0.0/Editor/Data/Nodes/Channel/SwizzleNode.cs:39)

System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object\[] parameters, System.Globalization.CultureInfo culture) (at <5300661a2d494f21a21307977ce92afb>:0)

Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.

System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object\[] parameters, System.Globalization.CultureInfo culture) (at <5300661a2d494f21a21307977ce92afb>:0)

System.Reflection.RuntimePropertyInfo.SetValue (System.Object obj, System.Object value, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object\[] index, System.Globalization.CultureInfo culture) (at <5300661a2d494f21a21307977ce92afb>:0)

System.Reflection.PropertyInfo.SetValue (System.Object obj, System.Object value, System.Object\[] index) (at <5300661a2d494f21a21307977ce92afb>:0)

Error:
Assertion failed
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /Users/bokken/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:189)