Check if Tumblr LikedBy is accessible (not offline)

Checks if a Tumblr liked-by page is accessible (or not available/offline) before trying to crawl it.

src/TumblThree/TumblThree.Applications/Crawler/TumblrLikedByCrawler.cs

@@ -76,6 +76,14 @@ private async Task GetUrlsAsync()
             semaphoreSlim = new SemaphoreSlim(shellService.Settings.ConcurrentScans);
             trackedTasks = new List<Task>();
 
+            if (!await CheckIfLoggedInAsync())
+            {
+                Logger.Error("TumblrLikedByCrawler:GetUrlsAsync: {0}", "User not logged in");
+                shellService.ShowError(new Exception("User not logged in"), Resources.NotLoggedIn, blog.Name);
+                postQueue.CompleteAdding();
+                return;
+            }
+
             long pagination = CreateStartPagination();
 
             // TODO: find way to parallelize without losing content.
@@ -114,14 +122,6 @@ private async Task CrawlPageAsync(long pagination, int crawlerNumber)
 
         public override async Task IsBlogOnlineAsync()
         {
-            if (!await CheckIfLoggedInAsync())
-            {
-                Logger.Error("TumblrLikedByCrawler:GetUrlsAsync: {0}", "User not logged in");
-                shellService.ShowError(new Exception("User not logged in"), Resources.NotLoggedIn, blog.Name);
-                postQueue.CompleteAdding();
-                return;
-            }
-
             try
             {
                 await GetRequestAsync(blog.Url);