IE BHO DWebBrowserEvents2_Event.BeforeScriptExecute don't have webbrower.Document on page Refresh

I am writing a BHO for IE11. In the BHO I have exposed some methods using IExtension interface to be called by the JavaScript. The Code is below

    IWebBrowser2 _webBrowser2;
    
    int IObjectWithSite.SetSite(object site)
    {
    try
    {
    _site = site;
    
        if (site != null)
        {
            var serviceProv = (IServiceProvider)_site;
            var guidIWebBrowserApp = Marshal.GenerateGuidForType(typeof(IWebBrowserApp));
            var guidIWebBrowser2 = Marshal.GenerateGuidForType(typeof(IWebBrowser2));
    
            IntPtr intPtr;
            serviceProv.QueryService(ref guidIWebBrowserApp, ref guidIWebBrowser2, out intPtr);
    
            _webBrowser2 = (IWebBrowser2)Marshal.GetObjectForIUnknown(intPtr);
    
            ((DWebBrowserEvents2_Event)_webBrowser2).BeforeScriptExecute += S2_BeforeScriptExecute;
        }
        else
        {
            ((DWebBrowserEvents2_Event)_webBrowser2).BeforeScriptExecute -= S2_BeforeScriptExecute;
            _webBrowser2 = null;
        }
    
        return 0;
    }
    
    private void S2_BeforeScriptExecute(object pDispWindow)
    {
        dynamic window = _webBrowser2.Document.parentWindow;
        IExpando windowEx = (IExpando)window;
        windowEx.AddProperty("myExtension");
        window.myExtension = this;
    }

In this everything is working fine except that when user clicks on refresh button in IE, _webBrowser2.Document.parentWindow gives exception

System.NotSupportedException: Exception from HRESULT: 0x800A01B6
   at System.Dynamic.ComRuntimeHelpers.CheckThrowException(Int32 hresult, ExcepInfo& excepInfo, UInt32 argErr, String message)
   at CallSite.Target(Closure , CallSite , ComObject )
   at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
   at CallSite.Target(Closure , CallSite , ComObject )
   at CallSite.Target(Closure , CallSite , Object )
   at BHO.S2_BeforeScriptExecute(Object pDispWindow)

Also I have tried instance of SHDocVw.WebBrowser instead of IWebBrowser2, but still the same issue.

So is there any alternative to this or something else that works fine?