What could cause a PDFDocument to be undefined?

[fharper]

I'm loading a PDF using this code

let pdfDocument = await PDFDocument.load(base64, {
    ignoreEncryption: true
});
await pdfDocument.save({updateFieldAppearances: false})

console.log("PDF: " + pdfDocument.PDFDocument);

and it's giving me a undefined on two documents only. If I open them in a viewer and save them, they works, so there is definitely something wrong with those. Unfortunately, I cannot share them outside of my coworkers, hence my question.

I got this error, but from what I've read in other issues, it shouldn't give me a problem to load the PDF

Trying to parse invalid object: {"line":34,"column":6,"offset":9389})
Invalid object ref: 10 0 R
Trying to parse invalid object: {"line":77,"column":6,"offset":13551})
Invalid object ref: 17 0 R
Trying to parse invalid object: {"line":114,"column":6,"offset":15684})
Invalid object ref: 23 0 R

The documents are not protected, I can view them in multiple PDF viewer, the mime type is right, I have no headers error message, and they don't seem corrupted (I tried with more than one tool). I also tried with another library with Python since I known the library, and it is working when I try to do the equivalent.

They are PDF 1.7 format, with no Acrobat Form nor XFA ones. The only common thing with those two documents is that they were generated using "HP Exstream Version 9.0.107 64-bit"... I'm trying to check on this side also to see what could be different...

Anything else I should check that could help identify what is the problem with these PDFs? Is there other reasons than the one I listed (and checked, based on other issues) that could cause this problem? Any help appreciated :)

[fharper]

I moved this discussion as an issue: #1148