error-alert.dart

import 'package:flutter/material.dart';

Future<void> showErrorAlert(context, errorString, callback) {
  return showDialog<void>(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text('Authorization error'),
        content: Text(errorString),
        actions: <Widget>[
          FlatButton(
            child: Text('Open Dashboard'),
            onPressed: () async {
              Navigator.of(context).pop();
              callback();
            },
          ),
        ],
      );
    },
  );
}