Mutating Null Causes 'KV Error: EINVAL'

Use case
The document stored user profile information with an email field. The user clears his email and saves his profile.

Steps to reproduce

1. Create a new document

   {

   "name": "User1",

   "email": "email"

   }

1. Mutate the document using the .NET client 3.0.5.

   class Program

   {

   private static ICluster _cluster;

   static async Task Main(string[] args)

   {

   var userInfo = new

   {

   Name = "User1",

   Email = (string)null

   };

   _cluster = await Cluster.ConnectAsync("couchbase://localhost", "Administrator", "Password");

   var bucket = await _cluster.BucketAsync("items");

   await bucket.DefaultCollection().MutateInAsync("doc1", new[]

   {

   MutateInSpec.Upsert("name", userInfo.Name),

   MutateInSpec.Upsert("email", userInfo.Email)

   });

   _cluster.Dispose();

   }

   }

#The following exception is show:

Couchbase.Core.Exceptions.InvalidArgumentException

{"DispatchedFrom":null,"DispatchedTo":null,"DocumentKey":"doc1","ClientContextId":"19","Cas":0,"Status":4,"BucketName":"items","CollectionName":"_default","ScopeName":null,"Message":"KV Error: {Name=\"EINVAL\", Description=\"Invalid packet\", Attributes=\"internal,invalid-input\"}"}