Everything works fine but I get this exception. Can't figure out detail of it. Can somebody help please

 

System.ArgumentNullException occurred
  Message="Value cannot be null.\r\nParameter name: path"
  Source="CuteEditor"
  ParamName="path"
  StackTrace:
       at CuteEditor.EditorUtility.ProcessPhyPath(HttpContext context, Control ctrl, String path)