SmartTarget Error for Web 8 Application

Question

We are getting the below error in our application logs. But the error occurs sometimes only.

SmartTargetClaimStore:SmartTargetModule-context_PreRequestHandlerExecute(): Object reference not set to an instance of an object.

Please suggest where to look for the issue, as SmartTarget is a black box for us. TIA.

Update: Code that throws the above error. Please let me know if we need to add an additional check to handle the same.

#region HttpModule

/// <summary>
/// SmartTarget Module
/// </summary>
public class SmartTargetModule : IHttpModule
{
    /// <summary>
    /// Module Intialization
    /// </summary>
    /// <param name="context">Application Context which will be passed to this function by IIS Pipeline</param>
    public void Init(HttpApplication context)
    {
        context.PreRequestHandlerExecute += context_PreRequestHandlerExecute;
    }

    private void context_PreRequestHandlerExecute(object sender, EventArgs e)
    {
        try
        {
            HttpRequest request = HttpContext.Current.Request;
            if (request.Path != null && (request.ServerVariables["SCRIPT_NAME"].Contains(".aspx")))
            {
                NameValueCollection nvc = request.QueryString;
                string[] keys = nvc.AllKeys;
                //Reading all QueryString parameter adding them to AmbientClaimStore
                foreach (string key in keys)
                {
                    string value = nvc[key].ToString();
                    value = HttpUtility.UrlDecode(value);
                    value = value.Contains(":") ? value.Substring(0, value.IndexOf(":")) : value;
                    ClaimStoreManager.AddPredefinedClaimToStore(key.Trim().ToLower(), value.Trim().ToLower());
                }
            }
        }
        catch (Exception ex)
        {
            Log.Message(string.Format("SmartTargetClaimStore:SmartTargetModule-context_PreRequestHandlerExecute(): {0} ", ex.Message), System.Diagnostics.TraceEventType.Error);
            Log.Exception(ex);
        }
    }........

Answer 1

This looks like a custom-made HTTP Module for IIS made by or for you. In which case you'll need to check with whoever wrote that module.

From the naming alone, it seems to be a module that interacts with the ADF -- so perhaps it's not handling the case where the ADF isn't yet available (or some of the data it needs isn't available).