Visual Studio opens up instead of Shader graph Editor on opening the HD Lit Graph and "ArgumentException: Value Unknown is not present in the list of possible values" exception thrown in the console.

Steps to repro:
1. Open the attached project.
2. Right Click on Project View.
3. Create > Shader > HDRP > Lit Graph.
4. Select the newly created Shader Graph and open Shader Editor.

Actual Result: Visual Studio opens up instead of Shader graph Editor.
"ArgumentException: Value Unknown is not present in the list of possible values" exception thrown in the console.

Expected Result: Shader graph Editor opens with HD Lit Master node.

Reproducible on: 5.6.1, 5.3.1.

Working Fine in 5.2.3

Checked on Unity Version: 2019.1.0b6, 2019.2.0a8.

Environment:
Windows & Mac.

Stack trace:
Exception thrown while invoking [OnOpenAssetAttribute] method 'UnityEditor.ShaderGraph.ShaderGraphImporterEditor:OnOpenAsset (int,int)' : ArgumentException: Value Unknown is not present in the list of possible values
UnityEditor.UIElements.PopupField`1[T].set_value (T value) (at C:/buildslave/unity/build/Editor/Mono/UIElements/Controls/PopupField.cs:48)
UnityEditor.Experimental.Rendering.HDPipeline.Drawing.HDLitSettingsView.<.ctor>b__3_28 (UnityEditor.UIElements.PopupField`1[T] field) (at Library/PackageCache/com.unity.render-pipelines.high-definition@5.6.1-preview/Editor/Material/Lit/ShaderGraph/HDLitSettingsView.cs:55)
UnityEditor.Graphing.Util.UIUtilities.Add[T] (UnityEngine.UIElements.VisualElement visualElement, T elementToAdd, System.Action`1[T] action) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Util/UIUtilities.cs:53)
UnityEditor.Experimental.Rendering.HDPipeline.Drawing.HDLitSettingsView.<.ctor>b__3_1 (UnityEditor.ShaderGraph.Drawing.PropertyRow row) (at Library/PackageCache/com.unity.render-pipelines.high-definition@5.6.1-preview/Editor/Material/Lit/ShaderGraph/HDLitSettingsView.cs:53)
UnityEditor.Graphing.Util.UIUtilities.Add[T] (UnityEngine.UIElements.VisualElement visualElement, T elementToAdd, System.Action`1[T] action) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Util/UIUtilities.cs:53)
UnityEditor.Experimental.Rendering.HDPipeline.Drawing.HDLitSettingsView..ctor (UnityEditor.Experimental.Rendering.HDPipeline.HDLitMasterNode node) (at Library/PackageCache/com.unity.render-pipelines.high-definition@5.6.1-preview/Editor/Material/Lit/ShaderGraph/HDLitSettingsView.cs:49)
UnityEditor.Experimental.Rendering.HDPipeline.HDLitMasterNode.CreateCommonSettingsElement () (at Library/PackageCache/com.unity.render-pipelines.high-definition@5.6.1-preview/Editor/Material/Lit/ShaderGraph/HDLitMasterNode.cs:818)
UnityEditor.ShaderGraph.MasterNode`1[T].CreateSettingsElement () (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Data/Nodes/MasterNode.cs:150)
UnityEditor.ShaderGraph.Drawing.MaterialNodeView.Initialize (UnityEditor.ShaderGraph.AbstractMaterialNode inNode, UnityEditor.ShaderGraph.Drawing.PreviewManager previewManager, UnityEditor.Experimental.GraphView.IEdgeConnectorListener connectorListener) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Drawing/Views/MaterialNodeView.cs:180)
UnityEditor.ShaderGraph.Drawing.GraphEditorView.AddNode (UnityEditor.ShaderGraph.AbstractMaterialNode node) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Drawing/Views/GraphEditorView.cs:546)
UnityEditor.ShaderGraph.Drawing.GraphEditorView..ctor (UnityEditor.EditorWindow editorWindow, UnityEditor.ShaderGraph.GraphData graph, UnityEditor.Graphing.Util.MessageManager messageManager) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Drawing/Views/GraphEditorView.cs:215)
UnityEditor.ShaderGraph.Drawing.MaterialGraphEditWindow.Initialize (System.String assetGuid) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Drawing/MaterialGraphEditWindow.cs:534)
UnityEditor.ShaderGraph.ShaderGraphImporterEditor.ShowGraphEditWindow (System.String path) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Importers/ShaderGraphImporterEditor.cs:50)
UnityEditor.ShaderGraph.ShaderGraphImporterEditor.OnOpenAsset (System.Int32 instanceID, System.Int32 line) (at Library/PackageCache/com.unity.shadergraph@5.6.1/Editor/Importers/ShaderGraphImporterEditor.cs:60)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)