error<T>  static method 
Create an error result
Implementation
static FlagEvaluationResult<T> error<T>(
  String flagKey,
  T defaultValue,
  ErrorCode errorCode,
  String message, {
  String evaluatorId = '',
}) {
  return FlagEvaluationResult<T>(
    flagKey: flagKey,
    value: defaultValue,
    reason: 'ERROR',
    errorCode: errorCode,
    errorMessage: message,
    evaluatedAt: DateTime.now(),
    evaluatorId: evaluatorId,
  );
}