Link addition does not work on Firefox

[kasunvp]

The title is self-explanatory. But looks like this is directly related to pell library itself.
Try adding a link here on Firefox https://jaredreich.com/pell/

[PoslinskiNet]

Ref: jaredreich/pell#186

[bikalay]

I have the same problem
FF version: 79.0
OS: MacOS (but reproducible on windows too)

Steps to reproduce:

Open https://jaredreich.com/pell/
click link button, enter url to prompt, click ok, nothing appears in editor
if i select some text before, all works fine