Fix NullRef in analytics service

src/NzbDrone.Core/IndexerSearch/ReleaseAnalyticsService.cs

@@ -1,5 +1,7 @@
+using System.Collections.Generic;
 using System.Linq;
 using System.Net.Http;
+using NLog;
 using NzbDrone.Common.Cloud;
 using NzbDrone.Common.Http;
 using NzbDrone.Common.Serializer;
@@ -14,6 +16,7 @@ namespace NzbDrone.Core.IndexerSearch
         private readonly IHttpClient _httpClient;
         private readonly IHttpRequestBuilderFactory _requestBuilder;
         private readonly IAnalyticsService _analyticsService;
+        private readonly Logger _logger;
 
         public ReleaseAnalyticsService(IHttpClient httpClient, IProwlarrCloudRequestBuilder requestBuilder, IAnalyticsService analyticsService)
         {
@@ -24,7 +27,7 @@ namespace NzbDrone.Core.IndexerSearch
 
         public void HandleAsync(IndexerQueryEvent message)
         {
-            if (_analyticsService.IsEnabled)
+            if (_analyticsService.IsEnabled && message.QueryResult?.Releases != null)
             {
                 var request = _requestBuilder.Create().Resource("release/push").Build();
                 request.Method = HttpMethod.Post;
@@ -34,7 +37,7 @@ namespace NzbDrone.Core.IndexerSearch
                 var body = message.QueryResult.Releases.Select(x => new
                 {
                     Title = x.Title,
-                    Categories = x.Categories.Where(c => c.Id < 10000).Select(c => c.Id),
+                    Categories = x.Categories?.Where(c => c.Id < 10000).Select(c => c.Id) ?? new List<int>(),
                     Protocol = x.DownloadProtocol.ToString(),
                     Size = x.Size,
                     PublishDate = x.PublishDate