Steps to Reproduce

<pdfviewer src="test.pdf" hflex="1" vflex="1" />

test.pdf (not shared in public)

Current Result

several texts remain blank

Expected Result

all text renders

Debug Information

pdfviewer uses an older version of pdf.js
the latest 2.9.x doesn't have the problem

Workaround

add the latest versions of pdf.js and pdf.worker.js (pdf.src.js / pdf.worker.src.js for debugging) in

WEB-INF/classes/web/js/zkex/pdfviewer/ext