The default behavior is unwind, and unless the library is targeting something like bare metal embedded, in all likelihood will never resort to an aborting panic

The default behavior is unwind, and unless the library is targeting something like bare metal embedded, in all likelihood will never resort to an aborting panic. I'll bet $20 USD to the open source project of your choice that the authors of whatever PDF library was being referenced here did not go out of their way to abort on panic, and that it's just a normal unwind.