Don't show an alert when removing missing items

When transitioning to the new schema, you'll likely get albums that
don't exist, though we try to update as soon as possible when the artist
album list is pulled. My guess is a race condition between getting the
album list from the server and the cached albums from Core Data.

The easiest workaround is to just not show this message.

Submariner/SBSubsonicParsingOperation.swift

@@ -188,12 +188,27 @@ class SBSubsonicParsingOperation: SBOperation, XMLParserDelegate {
                 return
             }
 
-            if let currentPlaylistID = self.currentPlaylistID, let playlistToDelete = fetchPlaylist(id: currentPlaylistID) {
-                threadedContext.delete(playlistToDelete)
-            } else if let currentArtistID = self.currentArtistID, let artistToDelete = fetchArtist(id: currentArtistID) {
-                threadedContext.delete(artistToDelete)
-            } else if let currentAlbumID = self.currentAlbumID, let albumToDelete = fetchAlbum(id: currentAlbumID) {
-                threadedContext.delete(albumToDelete)
+            if let currentPlaylistID = self.currentPlaylistID {
+                logger.info("Didn't find playlist on server w/ ID of \(currentPlaylistID, privacy: .public)")
+                if let playlistToDelete = fetchPlaylist(id: currentPlaylistID) {
+                    logger.info("Removing playlist that wasn't found on server w/ ID of \(currentPlaylistID, privacy: .public)")
+                    threadedContext.delete(playlistToDelete)
+                }
+                return
+            } else if let currentArtistID = self.currentArtistID {
+                logger.info("Didn't find artist on server w/ ID of \(currentArtistID, privacy: .public)")
+                if let artistToDelete = fetchArtist(id: currentArtistID) {
+                    logger.info("Removing artist that wasn't found on server w/ ID of \(currentArtistID, privacy: .public)")
+                    threadedContext.delete(artistToDelete)
+                }
+                return
+            } else if let currentAlbumID = self.currentAlbumID {
+                logger.info("Didn't find album on server w/ ID of \(currentAlbumID, privacy: .public)")
+                if let albumToDelete = fetchAlbum(id: currentAlbumID) {
+                    logger.info("Removing album that wasn't found on server w/ ID of \(currentAlbumID, privacy: .public)")
+                    threadedContext.delete(albumToDelete)
+                }
+                return
             }
             // XXX: Cover, podcast, track? Do we need to remove it from any sets?
         }