Fix for corner case where there are no objects in the scene.

object_edit_linked.py

@@ -74,7 +74,7 @@ class EditLinked(bpy.types.Operator):
 
     @classmethod
     def poll(cls, context):
-        return settings["original_file"] == "" and (
+        return settings["original_file"] == "" and context.active_object is not None and (
                 (context.active_object.dupli_group and
                  context.active_object.dupli_group.library is not None) or
                  context.active_object.library is not None)
@@ -155,6 +155,10 @@ class PanelLinkedEdit(bpy.types.Panel):
     bl_space_type = "VIEW_3D"
     bl_region_type = "TOOLS"
 
+    @classmethod
+    def poll(cls, context):
+        return (context.active_object is not None) or (settings["original_file"] != "")
+
     def draw(self, context):
         layout = self.layout
         scene = context.scene