An OSError object holds information about an error from the operating system.

class OSError {
  /** Constant used to indicate that no OS error code is available. */
  static const int noErrorCode = -1;

  /** Creates an OSError object from a message and an errorCode. */
  const OSError([String this.message = "", int this.errorCode = noErrorCode]);

  /** Converts an OSError object to a string representation. */
  String toString() {
    throw UnsupportedOperationException('OSError.toString');
  }

  /**
    * Error message supplied by the operating system. null if no message is
    * associated with the error.
    */
  final String message;

  /**
    * Error code supplied by the operating system. Will have the value
    * [noErrorCode] if there is no error code associated with the error.
    */
  final int errorCode;
}