using afBeanUtils::NotFoundErr** Indicates the Err has a more interesting cause@NoDocmixin Unwrappable {abstract Err? cause()}** As thrown by IoCconstclass IocErr : Err, Unwrappable {** A trace of IoC operations that led to the Err. ** A succinct and more informative stack trace if you will.const Str? operationTraceinternalnew make(Str msg := "", Err? cause := null, Str? opTrace := null) : super(msg, cause){this.operationTrace = opTrace}override Str toStr(){ opTrace := (cause == null) ? "${typeof.qname}: " : (cause is IocErr ? "" : "${cause.typeof.qname}: ") opTrace += msgif(operationTrace != null && !operationTrace.isEmpty){ opTrace += "\nIoc Operation Trace:\n" operationTrace.splitLines.each |op, i| { opTrace += (" [${(i+1).toStr.justr(2)}] $op\n")} opTrace += "Stack Trace:"}return opTrace}}** Thrown when an impossible condition occurs. You know when - we've all written comments like:** ** '// this should never happen...' @NoDocconstclass WtfErr : Err {new make(Str msg, Err? cause := null) : super(msg, cause){}}