SearchAfter not working with nil

[jjauzion]

With the typeClient (v8) the SearchAfter takes a list of types.FieldValue where, according to the doc, a FieldValue is any of:

//	int64
//	Float64
//	string
//	bool
//	nil
//	json.RawMessage

So I would expect that a query with a nil value in the SearchAfter works the same as a query with no SearchAfter. But when I pass a nil value I get a 500 error:

"error": "status: 500, failed: [search_phase_execution_exception], reason: all shards failed"

Code example:

es, _ := elasticsearch.NewTypedClient(cfg)
res, err := es.Search().Index("myIndex").Request(&search.Request{
		Query: &types.Query{
			Match: map[string]types.MatchQuery{
				"field1": {Query: "value1"},
			},
		},
		Sort: types.Sort{types.SortOptions{
			SortOptions: map[string]types.FieldSort{
				"date": {
					Order: &sortorder.Desc,
				},
			},
		}},
		SearchAfter: []types.FieldValue{nil},
	}).Do(ctx)