Is there a limit to subclass levels to use the Where function for query?

Question

I am working on an internal statistical data system of my company and I came across a situation I had never seen before.

I am consulting the API of a service and this returns me a JSON with many entries and sub-entries. I converted this JSON into C# classes and started working on the information filters. It happens that if I make a filter using the WHERE function in a list in the fields of the first level the return is correct. However, if I do this on internal levels, I get an exception.

The classes of the created objects were:

    public class Associations
    {
        public List<int> associatedVids { get; set; }
        public List<object> associatedCompanyIds { get; set; }
        public List<object> associatedDealIds { get; set; }
        public List<object> associatedTicketIds { get; set; }
    }

    public class DealnameVersions
    {
        public string name { get; set; }
        public string value { get; set; }
        public long timestamp { get; set; }
        public string sourceId { get; set; }
        public string source { get; set; }
        public List<object> sourceVid { get; set; }
    }

    public class Dealname
    {
        public string value { get; set; }
        public long timestamp { get; set; }
        public string source { get; set; }
        public string sourceId { get; set; }
        public List<DealnameVersions> versions { get; set; }
    }

    public class HubspotOwnerIdVersions
    {
        public string name { get; set; }
        public string value { get; set; }
        public object timestamp { get; set; }
        public string sourceId { get; set; }
        public string source { get; set; }
        public List<object> sourceVid { get; set; }
        public string requestId { get; set; }
    }

    public class HubspotOwnerId
    {
        public string value { get; set; }
        public long timestamp { get; set; }
        public string source { get; set; }
        public string sourceId { get; set; }
        public List<HubspotOwnerIdVersions> versions { get; set; }
    }

    public class DealstageVersions
    {
        public string name { get; set; }
        public string value { get; set; }
        public object timestamp { get; set; }
        public string sourceId { get; set; }
        public string source { get; set; }
        public List<object> sourceVid { get; set; }
    }

    public class Dealstage
    {
        public string value { get; set; }
        public long timestamp { get; set; }
        public string source { get; set; }
        public string sourceId { get; set; }
        public List<DealstageVersions> versions { get; set; }
    }

    public class CidadeDeInteresseVersions
    {
        public string name { get; set; }
        public string value { get; set; }
        public long timestamp { get; set; }
        public string sourceId { get; set; }
        public string source { get; set; }
        public List<object> sourceVid { get; set; }
    }

    public class CidadeDeInteresse
    {
        public string value { get; set; }
        public long timestamp { get; set; }
        public string source { get; set; }
        public string sourceId { get; set; }
        public List<CidadeDeInteresseVersions> versions { get; set; }
    }

    public class Properties
    {
        public Dealname dealname { get; set; }
        public HubspotOwnerId hubspot_owner_id { get; set; }
        public Dealstage dealstage { get; set; }
        public CidadeDeInteresse cidade_de_interesse { get; set; }
    }

    public class Deal
    {
        public int portalId { get; set; }
        public int dealId { get; set; }
        public bool isDeleted { get; set; }
        public Associations associations { get; set; }
        public Properties properties { get; set; }
        public List<object> imports { get; set; }
        public List<object> stateChanges { get; set; }
    }

    public class DealsModel
    {
        public List<Deal> deals { get; set; }
        public bool hasMore { get; set; }
        public int offset { get; set; }
    }

The filters I’m doing this way:

reservationList.Where(x => x.properties.dealstage.value == funilItem.stageId);

Note the expression passing through the properties object, then the dealstage object and comparing with the value field.

In this format I have failed. An exception is generated with the following information:

'reservationList.Findall(x => x.properties.dealstage.value == funilItem.stageId)' threw an Exception of type 'System.Nullreferenceexception'

However, if you do the same query format only in the fields at the same level of properties, the process is performed successfully.

reservationList.Where(x => x.dealId == funilItem.stageId);

Now I ask. Is there any limitation with subclass levels or is there something more wrong with my code? How should I solve this problem?

I would like to take all Deals based on the "value" field contained within properties -> dealstage -> value.

Thank you very much in advance.