I've reported it and uploaded the pdf, so someone on IRC responsible could debug it, but we didn't get far enough to fix it. Otherwise I wouldn't just add another PDF Viewer to a site. But it's only the downloads section and the preview there really is not for reading, but looking if it's the right document. Anyway, thanks for caring for the project. There's a reason Mozilla chose PDF.js over writing it in C++ and that's not just because of security I think.