Handle cat API 404 responses

src/Nest/Cat/CatResponse.cs

@@ -8,6 +8,7 @@ namespace Nest
 	public class CatResponse<TCatRecord> : ResponseBase
 		where TCatRecord : ICatRecord
 	{
+		[IgnoreDataMember]
 		public IReadOnlyCollection<TCatRecord> Records { get; internal set; } = EmptyReadOnly<TCatRecord>.Collection;
 	}
 }

src/Nest/Cat/CatResponseBuilder.cs

@@ -12,23 +12,27 @@ internal class CatResponseBuilder<TCatRecord> : CustomResponseBuilderBase where
 
 		public override object DeserializeResponse(IElasticsearchSerializer builtInSerializer, IApiCallDetails response, Stream stream)
 		{
-			var catResponse = new CatResponse<TCatRecord>();
-
 			if (!response.Success)
-				return catResponse;
+				return new CatResponse<TCatRecord>();
 
+			if (response.HttpStatusCode == 404)
+				return builtInSerializer.Deserialize<CatResponse<TCatRecord>>(stream);
+
+			var catResponse = new CatResponse<TCatRecord>();
 			var records = builtInSerializer.Deserialize<IReadOnlyCollection<TCatRecord>>(stream);
 			catResponse.Records = records;
 			return catResponse;
 		}
 
 		public override async Task<object> DeserializeResponseAsync(IElasticsearchSerializer builtInSerializer, IApiCallDetails response, Stream stream, CancellationToken ctx = default)
 		{
-			var catResponse = new CatResponse<TCatRecord>();
-
 			if (!response.Success)
-				return catResponse;
+				return new CatResponse<TCatRecord>();
 
+			if (response.HttpStatusCode == 404)
+				return await builtInSerializer.DeserializeAsync<CatResponse<TCatRecord>>(stream, ctx).ConfigureAwait(false);
+
+			var catResponse = new CatResponse<TCatRecord>();
 			var records = await builtInSerializer.DeserializeAsync<IReadOnlyCollection<TCatRecord>>(stream, ctx).ConfigureAwait(false);
 			catResponse.Records = records;
 			return catResponse;

src/Tests/Tests/Cat/CatCount/CatCountApiTests.cs

@@ -49,4 +49,29 @@ protected override LazyResponses ClientUsage() => Calls(
 		protected override void ExpectResponse(CatResponse<CatCountRecord> response) =>
 			response.Records.Should().NotBeEmpty().And.Contain(a => a.Count != "0" && !string.IsNullOrEmpty(a.Count));
 	}
+
+	public class CatCountNonExistentIndexApiTests
+		: ApiIntegrationTestBase<ReadOnlyCluster, CatResponse<CatCountRecord>, ICatCountRequest, CatCountDescriptor, CatCountRequest>
+	{
+		public CatCountNonExistentIndexApiTests(ReadOnlyCluster cluster, EndpointUsage usage) : base(cluster, usage) { }
+
+		protected override bool ExpectIsValid => false;
+		protected override int ExpectStatusCode => 404;
+		protected override HttpMethod HttpMethod => HttpMethod.GET;
+		protected override string UrlPath => "/_cat/count/non-existent-index";
+
+		protected override LazyResponses ClientUsage() => Calls(
+			(client, f) => client.Cat.Count(c => c.Index("non-existent-index")),
+			(client, f) => client.Cat.CountAsync(c => c.Index("non-existent-index")),
+			(client, r) => client.Cat.Count(new CatCountRequest("non-existent-index")),
+			(client, r) => client.Cat.CountAsync(new CatCountRequest("non-existent-index"))
+		);
+
+		protected override void ExpectResponse(CatResponse<CatCountRecord> response)
+		{
+			response.ApiCall.Success.Should().BeTrue();
+			response.ServerError.Should().NotBeNull();
+			response.Records.Should().NotBeNull().And.BeEmpty();
+		}
+	}
 }