Fixed: (GazelleGames) Serialization error on empty response

Fixes #1137

src/NzbDrone.Core.Test/Files/Indexers/GazelleGames/recentfeed-empty.json

@@ -0,0 +1,4 @@
+{
+  "status": "success",
+  "response": []
+}

src/NzbDrone.Core.Test/IndexerTests/GazelleGamesTests/GazelleGamesFixture.cs

@@ -12,6 +12,7 @@ using NzbDrone.Core.Indexers.Definitions;
 using NzbDrone.Core.IndexerSearch.Definitions;
 using NzbDrone.Core.Parser.Model;
 using NzbDrone.Core.Test.Framework;
+using NzbDrone.Test.Common;
 
 namespace NzbDrone.Core.Test.IndexerTests.GazelleGamesTests
 {
@@ -64,5 +65,19 @@ namespace NzbDrone.Core.Test.IndexerTests.GazelleGamesTests
             torrentInfo.DownloadVolumeFactor.Should().Be(1);
             torrentInfo.UploadVolumeFactor.Should().Be(1);
         }
+
+        [Test]
+        public async Task should_not_error_if_empty_response()
+        {
+            var recentFeed = ReadAllText(@"Files/Indexers/GazelleGames/recentfeed-empty.json");
+
+            Mocker.GetMock<IIndexerHttpClient>()
+                .Setup(o => o.ExecuteProxiedAsync(It.Is<HttpRequest>(v => v.Method == HttpMethod.Get), Subject.Definition))
+                .Returns<HttpRequest, IndexerDefinition>((r, d) => Task.FromResult(new HttpResponse(r, new HttpHeader { { "Content-Type", "application/json" } }, new CookieCollection(), recentFeed)));
+
+            var releases = (await Subject.Fetch(new BasicSearchCriteria { Categories = new int[] { 2000 } })).Releases;
+
+            releases.Should().HaveCount(0);
+        }
     }
 }

src/NzbDrone.Core/Indexers/Definitions/GazelleGames.cs

@@ -341,7 +341,18 @@ namespace NzbDrone.Core.Indexers.Definitions
                 return torrentInfos;
             }
 
-            foreach (var result in jsonResponse.Resource.Response)
+            Dictionary<string, GazelleGamesGroup> response;
+
+            try
+            {
+                response = ((JObject)jsonResponse.Resource.Response).ToObject<Dictionary<string, GazelleGamesGroup>>();
+            }
+            catch
+            {
+                return torrentInfos;
+            }
+
+            foreach (var result in response)
             {
                 Dictionary<string, GazelleGamesTorrent> torrents;
 
@@ -455,7 +466,7 @@ namespace NzbDrone.Core.Indexers.Definitions
     public class GazelleGamesResponse
     {
         public string Status { get; set; }
-        public Dictionary<string, GazelleGamesGroup> Response { get; set; }
+        public object Response { get; set; }
     }
 
     public class GazelleGamesGroup