NullRef in JsonLd to be investigated

[serialseb]

System.NullReferenceException: Object reference not set to an instance of an object.
   at OpenRasta.Plugins.Hydra.Internal.Serialization.JsonLdCodecWriter.WriteTo(Object entity, IHttpEntity response, IEnumerable`1 codecParameters) in /_/src/OpenRasta.Plugins.Hydra/Internal/Serialization/JsonLdCodecWriter.cs:line 45
   at OpenRasta.Pipeline.Contributors.ResponseEntityWriterContributor.WriteResponseEntity(ICommunicationContext context)
   at OpenRasta.Pipeline.ResponseMiddleware.InvokeCore(ICommunicationContext env) in /_/src/OpenRasta/Pipeline/ResponseMiddleware.cs:line 27
   at OpenRasta.Pipeline.ResponseMiddleware.InvokeCore(ICommunicationContext env) in /_/src/OpenRasta/Pipeline/ResponseMiddleware.cs:line 44
   at OpenRasta.Pipeline.ResponseMiddleware.InvokeCore(ICommunicationContext env) in /_/src/OpenRasta/Pipeline/ResponseMiddleware.cs:line 44
   at OpenRasta.Pipeline.ResponseMiddleware.InvokeCore(ICommunicationContext env) in /_/src/OpenRasta/Pipeline/ResponseMiddleware.cs:line 44
   at OpenRasta.Pipeline.ResponseMiddleware.InvokeCore(ICommunicationContext env) in /_/src/OpenRasta/Pipeline/ResponseMiddleware.cs:line 44
   at OpenRasta.Pipeline.ResponseRetryMiddleware.ShouldRetryRendering(ICommunicationContext env) in /_/src/OpenRasta/Pipeline/ResponseRetryMiddleware.cs:line 76