Fix nullable warnings in SpotifyMissingTracksFetcher

allstarr/Services/Spotify/SpotifyMissingTracksFetcher.cs

@@ -251,6 +251,13 @@ public class SpotifyMissingTracksFetcher : BackgroundService
         var settings = _spotifySettings.Value;
         var jellyfinUrl = _jellyfinSettings.Value.Url;
         var apiKey = _jellyfinSettings.Value.ApiKey;
+        
+        if (string.IsNullOrEmpty(jellyfinUrl) || string.IsNullOrEmpty(apiKey))
+        {
+            _logger.LogWarning("Jellyfin URL or API key not configured, skipping fetch for {Playlist}", playlistName);
+            return;
+        }
+        
         var httpClient = _httpClientFactory.CreateClient();
         
         // Start from the configured sync time (most likely time)