.NET Function app and pdfium; Could not load file or assembly 'System.Windows.Forms'

Question

I am trying to receive a base64 string as a PDF and print it out.

I have this code:

public void PrintPdfFromBase64(string base64String, string printerName)
{
    byte[] pdfBytes = Convert.FromBase64String(base64String);
    string tempFilePath = Path.GetTempFileName() + ".pdf";
    File.WriteAllBytes(tempFilePath, pdfBytes);

    try
    {
        using (var pdfStream = new MemoryStream(pdfBytes))
        {
            using (var document = PdfiumViewer.PdfDocument.Load(pdfStream))
            {
                var printDocument = document.CreatePrintDocument();
                printDocument.PrinterSettings = new PrinterSettings
                {
                    PrinterName = printerName  
                };

                printDocument.PrinterSettings.Copies = 1;  
                printDocument.DefaultPageSettings.Landscape = false;  
                printDocument.Print();
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"An error occurred while printing: {ex.Message}");
    }
    finally
    {
        // Clean up the temporary file
        File.Delete(tempFilePath);
    }
}

I installed pdfium nuget package, together with these:

However, when I send a print job it crashes with:

Could not load file or assembly 'System.Windows.Forms'

I am running an ASP.NET Core 8 app.

Has anyone had any experience with this?