OpenTween.TweenMain.CheckNewVersion C# (CSharp) Method

        private async Task CheckNewVersion(bool startup = false)
        {
            if (ApplicationSettings.VersionInfoUrl == null)
                return; // 更新チェック無効化

            try
            {
                var versionInfo = await this.GetVersionInfoAsync();

                if (versionInfo.Version <= Version.Parse(MyCommon.FileVersion))
                {
                    // 更新不要
                    if (!startup)
                    {
                        var msgtext = string.Format(Properties.Resources.CheckNewVersionText7,
                            MyCommon.GetReadableVersion(), MyCommon.GetReadableVersion(versionInfo.Version));
                        msgtext = MyCommon.ReplaceAppName(msgtext);

                        MessageBox.Show(msgtext,
                            MyCommon.ReplaceAppName(Properties.Resources.CheckNewVersionText2),
                            MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                    return;
                }

                using (var dialog = new UpdateDialog())
                {
                    dialog.SummaryText = string.Format(Properties.Resources.CheckNewVersionText3,
                        MyCommon.GetReadableVersion(versionInfo.Version));
                    dialog.DetailsText = versionInfo.ReleaseNote;

                    if (dialog.ShowDialog(this) == DialogResult.Yes)
                    {
                        await this.OpenUriInBrowserAsync(versionInfo.DownloadUri.OriginalString);
                    }
                }
            }
            catch (Exception)
            {
                this.StatusLabel.Text = Properties.Resources.CheckNewVersionText9;
                if (!startup)
                {
                    MessageBox.Show(Properties.Resources.CheckNewVersionText10,
                        MyCommon.ReplaceAppName(Properties.Resources.CheckNewVersionText2),
                        MessageBoxButtons.OK, MessageBoxIcon.Exclamation, MessageBoxDefaultButton.Button2);
                }
            }
        }