Null-conditional operator in Expression.PropertyOrField

Question

I'm trying to build a function that will sort a list of T by specified field (as a string name of the field), including fields in nested objects. I can create expression like this: l.FooObject.Name, but I don't know how to create an expression like this: l.FooObject?.Name or at least like this (l.FooObject == null) ? default : l.FooObject.Name

This is my function:

public static List<T> Sort(List<T> sourceList, string sortBy)
{
    var propertyNames = sortBy.Split('.');
    var parameter = Expression.Parameter(typeof(T), "x");

    Expression propertyAccess = parameter;
    foreach (var propertyName in propertyNames)
    {
        propertyAccess = Expression.PropertyOrField(propertyAccess, propertyName);
    }

    var propertyValue = Expression.Convert(propertyAccess, typeof(object));
    var sortExpression = Expression.Lambda<Func<T, object>>(propertyValue, parameter);

    var query = sourceList.AsQueryable();
    query = query.OrderBy(sortExpression);
    return query.ToList();
}

The problem is this line: propertyAccess = Expression.PropertyOrField(propertyAccess, propertyName);

The expression created by this function will throw System.NullReferenceException if Nested object is null. For example having these two classes:

public class Foo
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

public class Bar
{
    public int Id { get; set; }
    public Foo? FooObject { get; set; }
}

If I want to sort List<Bar> by "FooObject.Name" it will throw an exception if there is at least one Bar object with null FooObject. It will build expression like this l.FooObject.Name. I need l.FooObject?.Name

Thanks for help!