Fixed: SourceTitle if Album Title null in Discord ImportFailed event

Fixes #2134

src/NzbDrone.Core/Notifications/Discord/Discord.cs

@@ -299,7 +299,7 @@ namespace NzbDrone.Core.Notifications.Discord
                         IconUrl = "https://raw.githubusercontent.com/lidarr/Lidarr/develop/Logo/256.png"
                     },
                     Description = message.Message,
-                    Title = message.Album.Title,
+                    Title = message.Album?.Title ?? message.Message,
                     Text = message.Message,
                     Color = (int)DiscordColors.Warning
                 }

src/NzbDrone.Core/Notifications/NotificationService.cs

@@ -241,7 +241,7 @@ namespace NzbDrone.Core.Notifications
             // TODO: Build out this message so that we can pass on what failed and what was successful
             var downloadMessage = new AlbumDownloadMessage
             {
-                Message = GetAlbumIncompleteImportMessage(message.TrackedDownload.DownloadItem.Title),
+                Message = GetAlbumIncompleteImportMessage(message.TrackedDownload.DownloadItem.Title)
             };
 
             foreach (var notification in _notificationFactory.OnImportFailureEnabled())