update method Null safety

Implementation

Future<void> update() async {
  if (_disposed) {
    return;
  }

  final bool hasStrings;
  try {
    hasStrings = await Clipboard.hasStrings();
  } catch (exception, stack) {
    FlutterError.reportError(FlutterErrorDetails(
      exception: exception,
      stack: stack,
      library: 'widget library',
      context: ErrorDescription('while checking if the clipboard has strings'),
    ));
    // In the case of an error from the Clipboard API, set the value to
    // unknown so that it will try to update again later.
    if (_disposed || value == ClipboardStatus.unknown) {
      return;
    }
    value = ClipboardStatus.unknown;
    return;
  }

  final ClipboardStatus nextStatus = hasStrings
      ? ClipboardStatus.pasteable
      : ClipboardStatus.notPasteable;

  if (_disposed || nextStatus == value) {
    return;
  }
  value = nextStatus;
}