Sitecore Custom Computed Date Field

DateField.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <contentSearch>
      <indexConfigurations>
        <CustomIndexConfiguration type="ToTheCoreSk.SC.Foundation.Search.AlgoliaIndexConfiguration, ToTheCoreSk.SC.Foundation.Search">
          <DocumentOptions type="Sitecore.ContentSearch.DocumentBuilderOptions, Sitecore.ContentSearch">
            <fields hint="raw:AddComputedIndexField">
              <field fieldName="Date" referencedFieldName="__Updated" dateFormatPattern="yyyyMMdd">ToTheCoreSk.SC.Foundation.Search.ComputedFields.DateField, ToTheCoreSk.SC.Foundation.Search</field>
            </fields>
          </DocumentOptions>
        </CustomIndexConfiguration>
      </indexConfigurations>
    </contentSearch>
  </sitecore>
</configuration>

DateField.cs

using System.Globalization;
using System.Xml;
using Sitecore.ContentSearch;
using Sitecore.ContentSearch.ComputedFields;
using Sitecore.ContentSearch.Diagnostics;
using Sitecore.Xml;

namespace ToTheCoreSk.SC.Foundation.Search.ComputedFields
{
    public class DateField : IComputedIndexField
    {
        public DateField(XmlNode configurationNode)
        {
            FieldName = XmlUtil.GetAttribute("fieldName", configurationNode);
            ReferencedFieldName = XmlUtil.GetAttribute("referencedFieldName", configurationNode);
            DateFormatPattern = XmlUtil.GetAttribute("dateFormatPattern", configurationNode);
        }
        
        public string FieldName { get; set; }
        
        public string ReturnType { get; set; }
        
        public string ReferencedFieldName { get; set; }
        
        public string DateFormatPattern { get; set; }
        
        public virtual object ComputeFieldValue(IIndexable indexable)
        {
            var item = (SitecoreIndexableItem)indexable;
            
            if (item?.Item == null)
            {
                CrawlingLog.Log.Error("DateField: indexable is not provided");
                return string.Empty;
            }
            
            if (string.IsNullOrEmpty(FieldName))
            {
                CrawlingLog.Log.Error("DateField: FieldName is not provided");
                return string.Empty;
            }
            
            var field = (Sitecore.Data.Fields.DateField)item.Item.Fields[ReferencedFieldName];
            
            if (field == null)
            {
                CrawlingLog.Log.Debug($"DateField: Cannot find field '{ReferencedFieldName}'");
                return string.Empty;
            }
            
            if (string.IsNullOrEmpty(DateFormatPattern))
            {
                CrawlingLog.Log.Debug($"DateField: DateFormatPattern is not provided");
                return string.Empty;
            }
           
            return field.DateTime.ToString(DateFormatPattern, CultureInfo.InvariantCulture);
        }
    }
}