DoubleWithFractionalPortionConverter and FloatWithFractionalPortionConverter should not fall through to always throw a JSONException for non NETCore builds

Author: karl-sjogren

src/Elastic.Clients.Elasticsearch/Serialization/DoubleWithFractionalPortionConverter.cs

@@ -75,6 +75,7 @@ public override void Write(Utf8JsonWriter writer, double value, JsonSerializerOp
 				if (bytes.Length < utf8bytes.Length)
 				{
 					bytes.CopyTo(utf8bytes);
+					return;
 				}
 			}
 			catch

src/Elastic.Clients.Elasticsearch/Serialization/FloatWithFractionalPortionConverter.cs

@@ -75,6 +75,7 @@ public override void Write(Utf8JsonWriter writer, float value, JsonSerializerOpt
 				if (bytes.Length < utf8bytes.Length)
 				{
 					bytes.CopyTo(utf8bytes);
+					return;
 				}
 			}
 			catch