error.go
func (err *Error) ErrorStack() string {
	return err.TypeName() + " " + err.Error() + "\n" + string(err.Stack())
}
func (err *Error) ErrorStack() string {
	return err.TypeName() + " " + err.Error() + "\n" + string(err.Stack())
}
// ErrorStack returns a string that contains both the
// error message and the callstack.