Numerals read as \u0000 when using font feature settings

[SimonEggert]

First of all, thanks for the work and effort you've put into this great library!

Bug description

We are having an issue with numerals not being read correctly by PDF::Inspector::Text.analyze. They get misinterpreted as \u0000 when we use font-feature-settings: 'tnum' as style. We are generating the PDF with Gotenberg from HTML templates.

Minimal reproducible example

<div>21.09.2023</div> gets read as 21.09.2023

while

<div style="font-feature-settings: 'tnum'">21.09.2023</div>gets read as \u0000\u0000.\u0000\u0000.\u0000\u0000\u0000\u0000.

PDFs

Here are two PDFs, one with the feature turned off and one with the feature turned on:
font_features_off.pdf
font_features_on.pdf

Further information

The UNIX tool pdftotext is able to read both versions correctly so I think the PDF is alright.
The font in use is Barlow if that makes any difference.

Any help would be appreciated!

P.S.: I'll also open an issue regarding this problem over at https://github.com/yob/pdf-reader so feel free to close this one if you think it should be handled there.