Convert HTML to PDF using C# and Aspose.PDF - Null Reference Exception

I am trying to convert html w/ css to pdf using the following code:

public static Byte[] ConvertHtmlToPdf(string htmlContent)
{
    Document doc = new Document();
    Page page = doc.Pages.Add();
    HtmlFragment htmlFragment = new HtmlFragment(htmlContent);
    page.Paragraphs.Add(htmlFragment);
    using (var finalPdfStream = new MemoryStream())
    {
        doc.Save(finalPdfStream);
        return finalPdfStream.ToArray();
    }
}

The following is the exception I am getting on doc.Save(finalPdfStream);

“Object reference not set to an instance of an object.”
at #=z4dG9O$SGimzqslY4y4EK9YouRsk8.#=zFFwysIit6tKcim4Sh_n1FXc=(#=zhwp_YZ2gQWjGuUNGGfvnL0g= #=zsM12MuI=, Page #=zl1Idajw=, Matrix #=zYK6UuYinzbWz)
at #=z4dG9O$SGimzqslY4y4EK9YouRsk8.#=z$Sqc12o=(#=zhwp_YZ2gQWjGuUNGGfvnL0g= #=zsM12MuI=, Boolean #=zhj9xbjUAYNvHAiT$Ug==, Page #=zl1Idajw=, Matrix #=zqJSt0cI=, #=z_g4ovMMHyhb0TFC6ZZtmu6djbRGT #=z2AEEsb4=)
at #=zGosD9uVfyFIrHJcS5tR0gKShjal1i9R4Qfugt98=.#=z23LL_wRXGGDC(#=zhwp_YZ2gQWjGuUNGGfvnL0g= #=zmRmKv9U=)
at #=zB_sjNI4IM5dx139qpi$vxT2cDDAv.#=zM08xx$PPFsko(#=zB_sjNI4IM5dx139qpi$vxR1OPhpWCJrUgw== #=zJm0iyTc=, #=zcFNJrT3xBrG$3w6$t50Q00vnM6lk7vQ7jA== #=z8_y2nyTT1PHB, RectangleF #=zS0tllaqETUK1Z6Q2Cw==)
at #=zB_sjNI4IM5dx139qpi$vxT2cDDAv.#=zSQaN2Vdh9baI(#=zsLrUsqHWchjqOsAlsNZOB7bM1xoELdh8PA== #=zAfc0d7Y=, Boolean #=zfS62rLaUb8_z)
at #=zB_sjNI4IM5dx139qpi$vxT2cDDAv.#=zcUwg7DOdiISWNEZUsw==(#=zMLpeDD7vvDhBYv90tPgQBHUUKOHTduiSkw== #=zYuJKqag=, Boolean #=zCaJ6M6xugtUfQ$TO2w==)
at #=zB_sjNI4IM5dx139qpi$vxT2cDDAv.#=zE_3gB4gFjgQw$OgACA==(#=z928VsAdYf10Fo_mWtg== #=zMy3wXN90JKUnkQliiA==, Boolean #=zCaJ6M6xugtUfQ$TO2w==, #=zDTJX2vxJRq19xU$GFL7vSR0bUZiDYd2iqQ== #=zFtkiu8o=)
at #=zB_sjNI4IM5dx139qpi$vxT2cDDAv.#=zYMC3DH8=(#=z7Lcr0Wi4iRhF4aljwAnqvNaotfquKevhuA== #=zl1Idajw=, #=zj_uML03auP4xDG_PjA== #=zMy3wXN90JKUnkQliiA==, Boolean #=zCaJ6M6xugtUfQ$TO2w==, #=zDTJX2vxJRq19xU$GFL7vSR0bUZiDYd2iqQ== #=zFtkiu8o=)
at #=zFA1zQZzuuc3e4ZCfPGlJmvwcdaUeYqNmsA==.Render(#=zxjaEqqZzqH_wklbqvOevNXkom$n1 #=zA_3cdh8=)
at #=zdECeIix1PFR_cvEpFAM2EWPCNDTkkwBBLw==.#=zxCaOzQ3SyRJ6(#=zCNKLl6ZK6t_$ibi3QHGgJQQ= #=zu2a_hiU5A2E5oWP$vg==, #=zdV34GEBBmB1RFjYTck02YVlmuF1U[] #=zzx0LmkFgQtlO, #=zxjaEqqZzqH_wklbqvOevNXkom$n1 #=zA_3cdh8=, TimeSpan #=z1KolkUA=)
at #=z6o$lwG1ep_MUIRZSKQO3hMiXMgXN.Render(#=zxjaEqqZzqH_wklbqvOevNXkom$n1 #=zA_3cdh8=, TimeSpan #=z1KolkUA=, #=zLM_61$kxoK5g$ui$Gt5aw3k=[] #=zHupSi1s=, #=zh$QvVhNG2b5Df43s6nuy6FM=[] #=zHFl$AkM=)
at #=z6o$lwG1ep_MUIRZSKQO3hMiXMgXN.Render(#=zxjaEqqZzqH_wklbqvOevNXkom$n1 #=zA_3cdh8=, TimeSpan #=z1KolkUA=, #=zh$QvVhNG2b5Df43s6nuy6FM=[] #=zHFl$AkM=)
at #=zzFcSCga_1l91mfA3frAONgBrSPdb.Render(#=zxjaEqqZzqH_wklbqvOevNXkom$n1 #=zA_3cdh8=, #=zPNtTwYU= #=zqgQFGbg=, TimeSpan #=z1KolkUA=)
at #=zzFcSCga_1l91mfA3frAONgBrSPdb.Render(#=zxjaEqqZzqH_wklbqvOevNXkom$n1 #=zA_3cdh8=, #=zPNtTwYU= #=zqgQFGbg=)
at #=z4OfvUXA_5PbOEr22TnfmTiADgaGw.#=zW4wLc6cAPlqM(Stream #=zWi8MGzGzqD2d, Document #=zB0HPh9mvVYYA, HtmlLoadOptions #=zEBpf2wDmyZfK, IList1 #=z_t3BLnpkUVl6, String #=zHA_GpvGmhOYq, Matrix #=zqJSt0cI=) at Aspose.Pdf.FormattedFragment.#=zgJt75F8=(Double& #=ze9zCUI8=, Double& #=zG6eHln4=, Boolean #=zIGzUGMqSAge_, Double #=zsfBlMBE=, Double #=zzvGdmLY=, List1 #=zwmkIGuY=, List`1 #=zNw7SXJgQfBt$9nP$Uw==, Int32& #=zM6HKcghiAAG2jsUNFM1I03PqlLxv, Page #=zl1Idajw=, MarginInfo #=z_tbIkIo=, Table #=zN8AunJ8=, Double& #=zw3N7flecUgqI, Boolean #=zJGjPzmc6Gibi, Boolean #=zlmCJ0wGHhfrG)
at #=z23HkmSbCnCFCayBy9yuaupM=.#=zgJt75F8=()
at Aspose.Pdf.Page.#=zAYJqtD0=(Page #=zl1Idajw=)
at Aspose.Pdf.Document.ProcessParagraphs()
at Aspose.Pdf.Document.#=zdU2_5jr8OKXN(Stream #=z0q$LhCM=, SaveOptions #=zyB_z4xR5rBy4)
at Aspose.Pdf.Document.Save(Stream output)
at AsposeHelpers.ConvertHtmlToPdf(String htmlContent) in C:\Dev\somepath\AsposeHelpers.cs:line 201

Attached is the html used that caused the error. When I remove the background-image: linear gradient in the 2 places there is no exception and it generates as expected.sample.zip (974 Bytes)

@rrogers,

I just tested the following code to load the Html and it works fine:

private void Logic()
{
    var option = new HtmlLoadOptions() { };

    var doc = new Document($"{PartialPath}_input.html", option);

    doc.Save($"{PartialPath}_output.pdf");      
}

The output file:
HtmlBackgroundImageCrashing_output.pdf (240.2 KB)

I am using Aspose PDF 23.1.1.