Add description to a new/existing apk and publish to Google Play

Question

I have the following code to publish apk to Google Play:

public async Task<GooglePlayAPIResult> Publish(Stream apk, string packageName, string title, string description)
{   
             using (var svc = new AndroidPublisherService(new BaseClientService.Initializer { HttpClientInitializer = _credentials }))
             {                                   
               AppEdit edit = await svc.Edits.Insert(new AppEdit(), packageName).ExecuteAsync();                    
               var success = await svc.Edits.Apks.Upload(packageName, edit.Id, apk, "application/octet-stream").UploadAsync();
               if (success.Exception != null)
                  throw success.Exception;
               var request = await svc.Edits.Listings.Update(new Listing { Title = title, FullDescription = description, ShortDescription = description }, packageName, edit.Id, "en-US").ExecuteAsync();
               // check status and throw an exception if it fails
               var commit = await svc.Edits.Commit(packageName, edit.Id).ExecuteAsync();
             }
             return new GooglePlayAPIResult { Success = true };
 }

How do I check the status of request and throw an exception if it fails?

Also, here is the code for creating a new app:

private async Task<GooglePlayAPIResult> Create(Stream apk, string title)
{
    using (var svc = new PlaycustomappService(new BaseClientService.Initializer { HttpClientInitializer = _credentials }))
    {
       var created = await svc.Accounts.CustomApps.Create( new CustomApp { Title = title, LanguageCode = "en_US" },
       _developerId, apk, "application/octet-stream").UploadAsync();
                    
       if (created.Exception != null)
       {
           return new GooglePlayAPIResult { Success = false, Error = (created.Exception as GoogleApiException).Error.Message };
       }

       // add description
   }
   return new GooglePlayAPIResult { Success = true };
}

How do I add description and check it's status?