Deserializer throws for empty literal string

[tpluscode]

Submitting a literal like

{
  "@value": "",
  "@type": "xsd:integer"
}

Causes a null guard error:

[NullGuard] Return value of method 'System.Object JsonLD.Entities.Converters.JsonLdLiteralConverter::ReadJson(Newtonsoft.Json.JsonReader,System.Type,System.Object,Newtonsoft.Json.JsonSerializer)' is null.
   at JsonLD.Entities.Converters.JsonLdLiteralConverter.ReadJson(JsonReader reader, Type objectType, Object existingValue, JsonSerializer serializer)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.DeserializeConvertable(JsonConverter converter, JsonReader reader, Type objectType, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.SetPropertyValue(JsonProperty property, JsonConverter propertyConverter, JsonContainerContract containerContract, JsonProperty containerProperty, JsonReader reader, Object target)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(Object newObject, JsonReader reader, JsonObjectContract contract, JsonProperty member, String id)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
   at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType)
   at Newtonsoft.Json.Linq.JToken.ToObject(Type objectType, JsonSerializer jsonSerializer)
   at Newtonsoft.Json.Linq.JToken.ToObject[T](JsonSerializer jsonSerializer)
   at JsonLD.Entities.EntitySerializer.Deserialize[T](JToken jsonLd, JToken context, JObject frame)\n   at JsonLD.Entities.EntitySerializer.Deserialize[T](JToken jsonLd