NullReferenceException when selecting a .shader file in project view

Hi

I found a error(but it can be cleared in console) when selecting a .shader file in project view

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.ShaderForgeInspector.ShowShaderErrors (UnityEngine.Shader s)
UnityEditor.ShaderForgeInspector.ShowShaderCodeArea (UnityEngine.Shader s)
UnityEditor.ShaderForgeInspector.DrawUnitysInspector ()
UnityEditor.ShaderForgeInspector.OnInspectorGUI

()
UnityEditor.InspectorWindow.DrawEditor (UnityEditor.Editor editor, Int32 editorIndex, Boolean

forceDirty, System.Boolean& showImportedObjectBarNext, UnityEngine.Rect& importedObjectBarRect, Boolean

eyeDropperDirty) (at C:/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1211)
UnityEditor.DockArea:OnGUI()

I use Unity 5.2.0f3 Personal and ShaderForge v1.18