Mutating Null Causes 'KV Error: EINVAL'

Similar to https://issues.couchbase.com/browse/NCBC-2640, but for Go SDK.

 

When executing a mutation and trying to set `nil` as value, EINVAL is returned.

 

Example code that I'm using:

```

documentId := "hello1234"

// First we insert some stuff, then we try to alter it
_, errInsert := testDb.Collection.Insert(documentId, map[string]interface{}

{ "name": "hello", }

, nil)
require.NoError(t, errInsert)

_, errMutate := testDb.Collection.MutateIn(documentId, []gocb.MutateInSpec

{ gocb.UpsertSpec("name", nil, &gocb.UpsertSpecOptions\{CreatePath: true}

),
}, nil)

// --> This throws the error <---
require.NoError(t, errMutate)

```

 

Returned error:

 

invalid argument | {"status_code":4,"bucket":"bucket_test","scope":"_default","collection":"_default","error_name":"EINVAL","error_description":"Invalid packet","opaque":18,"last_dispatched_to":"192.168.1.109:11210","last_dispatched_from":"192.168.1.105:65378","last_connection_id":"2b9e1bcb4d45f655/7b20324a779687d1"}