//// Copyright (c) 2010, Brian Frank and Andy Frank// Licensed under the Academic Free License version 3.0//// History:// 23 Mar 10 Brian Frank Creation//**** FieldNotSetErr indicates a non-nullable field was not** set by the constructor it-block.**const class FieldNotSetErr : Err {**** Construct with specified error message and optional root cause.**new make(Str msg := "", Err? cause := null) }