I'm testing one of the top grossing assets on the A$: Amplify Shader.
Some chages introduced in the UnityEditor.EditorWindow causes the package to throw a Null Reference Exception now:
NullReferenceException: Object reference not set to an instance of an object
WindowHelper+R_DockArea.AddTab (UnityEditor.EditorWindow pane) (at Assets/AmplifyShaderEditor/Plugins/Editor/Utils/WindowHelper.cs:62)
WindowHelper.AddTab (UnityEditor.EditorWindow existingWindow, UnityEditor.EditorWindow newWindow) (at Assets/AmplifyShaderEditor/Plugins/Editor/Utils/WindowHelper.cs:149)
AmplifyShaderEditor.AmplifyShaderEditorWindow.ConvertShaderToASE (UnityEngine.Shader shader) (at Assets/AmplifyShaderEditor/Plugins/Editor/Menu/AmplifyShaderEditorWindow.cs:379)
UnityEditor.CustomShaderInspector.OnInspectorGUI () (at Assets/AmplifyShaderEditor/Plugins/Editor/Utils/CustomShaderInspector.cs:233)
UnityEditor.InspectorWindow.DoOnInspectorGUI (System.Boolean rebuildOptimizedGUIBlock, UnityEditor.Editor editor, System.Boolean wasVisible, UnityEngine.Rect& contentRect) (at C:/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1599)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

This prevents a button from opening the script in the graph editor.

Repro steps:
-open this project
-go to the Examples folder- you will see a few examples there.
-double-click on the shader object - that should open the graph editor
-in the inspector, while selecting the shader object, you will also find a button "open in Shader Editor" - that button also throws the same exception.