Texture2D MissingMethodException

If I add a Texture2D node to a shader, I get a stream of errors in the Console, and can't click-drag the node in the view (otherwise, it seems to work):

MissingMethodException: Method not found: 'UnityEditor.EditorGUIUtility.GetObjectPickerObject'.

UnityEngine.GUI.CallWindowDelegate (UnityEngine.WindowFunction func, Int32 id, UnityEngine.GUISkin _skin, Int32 forceRect, Single width, Single height, UnityEngine.GUIStyle style) (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/GUI.cs:1283)

UnityEditor.EditorWindow:EndWindows()

ShaderForge.SF_EditorNodeView:OnLocalGUI(Rect)

ShaderForge.SF_Editor:OnGUI()

UnityEditor.DockArea:OnGUI()

This is in Unity 4.1.5f1.