If document has no footer and header the result gets package missing

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C#3.5

using (MemoryStream destination = new MemoryStream())
{
    using (FileStream sourcefilecopy = File.Open(file,
        FileMode.Open))
    { sourcefilecopy.CopyTo(destination); }

    using (WordprocessingDocument doc = WordprocessingDocument.Open(destination, true))
    {
        var docPart = doc.MainDocumentPart;

        if(docPart.HeaderParts.Count() > 0 ||
            docPart.FooterParts.Count() > 0)
        {
            docPart.DeleteParts(docPart.HeaderParts);
            docPart.DeleteParts(docPart.FooterParts);
            Document document = docPart.Document;
            var headers = document.Descendants<HeaderReference>().ToList();
            foreach (var header in headers)
            {
                header.Remove();
            }

            var footers = document.Descendants<FooterReference>().ToList();
            foreach (var footer in footers)
            {
                footer.Remove();
            }
            document.Save();
        }
    }
}

This code makes a copy of a document using a mememorystream, then check if the cound > 0 on header and footer and removes it,
But if my document dont have any footer and header it get the error The specifield package is invalid the main part is missing