CS8600 Converting null literal or possible null value to non-nullable type when using Activator.CreateInstance

I am trying to use reflection to get classes based on the interface name. But when I try to create an instance of the class based on the type using CreateInstance() I am receiving the error CS8600 Converting null literal or possible null value to non-nullable type.

    public RequestEmailNotifyBehaviour()
    {
        IEnumerable<Type> emailNotifiers = GetTypesWithInterface(Assembly.GetExecutingAssembly());
        List<IEmailNotification<IRequest>> listOfNotifiers = new List<IEmailNotification<IRequest>>();
        foreach (Type type in emailNotifiers)
        {
            listOfNotifiers.Add((IEmailNotification<IRequest>)Activator.CreateInstance(type));         
        }
    }

    private IEnumerable<Type> GetTypesWithInterface(Assembly asm)
    {
        var it = typeof(IEmailNotification<TRequest>);
        return asm.GetLoadableTypes()
            .Where(it.IsAssignableFrom)
            .Where(t => !(t.Equals(it)))
            .ToList();
    }



public static class TypeLoaderExtensions
{
    public static IEnumerable<Type> GetLoadableTypes(this Assembly assembly)
    {
        if (assembly == null) throw new ArgumentNullException("assembly");
        try
        {
            return assembly.GetTypes();
        }
        catch (ReflectionTypeLoadException e)
        {
            return (IEnumerable < Type > ) e.Types.Where(t => t != null);
        }
    }
}