Dim WithEvents ScriptWindow As HtmlWindow

Private Sub SuppressScriptErrors()
    If (WebBrowser1.Document IsNot Nothing) Then
        ScriptWindow = WebBrowser1.Document.Window
    End If
End Sub

Private Sub ScriptWindow_Error(ByVal sender As Object, ByVal e As HtmlElementErrorEventArgs) Handles ScriptWindow.Error
    MessageBox.Show("Suppressed error!")
    e.Handled = True
End Sub

        private void SuppressScriptErrors()
        {
            if (webBrowser1.Document != null)
            {
                webBrowser1.Document.Window.Error += new HtmlElementErrorEventHandler(scriptWindow_Error);
            }
        }
        
        private void  scriptWindow_Error(object sender, HtmlElementErrorEventArgs e)
        {
             MessageBox.Show("Suppressed error!");
            e.Handled = true;
        }