Fix NPE when deserializing invalid SearchResponse (#8516) (#8517)

Co-authored-by: Florian Bernd <git@flobernd.de>

Author: github-actions[bot]

src/Elastic.Clients.Elasticsearch/_Shared/Api/SearchResponse.cs

@@ -11,10 +11,10 @@ namespace Elastic.Clients.Elasticsearch;
 public partial class SearchResponse<TDocument>
 {
 	[JsonIgnore]
-	public IReadOnlyCollection<Core.Search.Hit<TDocument>> Hits => HitsMetadata.Hits;
+	public IReadOnlyCollection<Core.Search.Hit<TDocument>> Hits => HitsMetadata?.Hits ?? [];
 
 	[JsonIgnore]
-	public IReadOnlyCollection<TDocument> Documents => HitsMetadata.Hits.Select(s => s.Source).ToReadOnlyCollection();
+	public IReadOnlyCollection<TDocument> Documents => HitsMetadata?.Hits?.Select(s => s.Source).ToReadOnlyCollection() ?? [];
 
 	[JsonIgnore]
 	public long Total => HitsMetadata?.Total?.Value1?.Value ?? HitsMetadata?.Total?.Value2 ?? -1;

src/Elastic.Clients.Elasticsearch/_Shared/Core/Infer/Field/FieldConverter.cs

@@ -22,6 +22,11 @@ public override Field Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSe
 
 	public override void Write(Utf8JsonWriter writer, Field value, JsonSerializerOptions options)
 	{
+		if (value is null)
+		{
+			throw new ArgumentNullException(nameof(value));
+		}
+
 		var settings = options.GetContext<IElasticsearchClientSettings>();
 		var fieldName = settings.Inferrer.Field(value);
 
@@ -37,6 +42,11 @@ public override Field ReadAsPropertyName(ref Utf8JsonReader reader, Type typeToC
 
 	public override void WriteAsPropertyName(Utf8JsonWriter writer, Field value, JsonSerializerOptions options)
 	{
+		if (value is null)
+		{
+			throw new ArgumentNullException(nameof(value));
+		}
+
 		var settings = options.GetContext<IElasticsearchClientSettings>();
 
 		writer.WritePropertyName(settings.Inferrer.Field(value));

src/Elastic.Clients.Elasticsearch/_Shared/Core/Infer/Fields/FieldsConverter.cs

@@ -21,6 +21,11 @@ public override Fields Read(ref Utf8JsonReader reader, Type typeToConvert, JsonS
 
 	public override void Write(Utf8JsonWriter writer, Fields value, JsonSerializerOptions options)
 	{
+		if (value is null)
+		{
+			throw new ArgumentNullException(nameof(value));
+		}
+
 		writer.WriteCollectionValue(options, value.ListOfFields, null);
 	}
 }
@@ -61,6 +66,11 @@ public override Fields Read(ref Utf8JsonReader reader, Type typeToConvert, JsonS
 
 	public override void Write(Utf8JsonWriter writer, Fields value, JsonSerializerOptions options)
 	{
+		if (value is null)
+		{
+			throw new ArgumentNullException(nameof(value));
+		}
+
 		writer.WriteSingleOrManyCollectionValue(options, value.ListOfFields, null);
 	}
 }