FR24 Feeder - Windows - 1.0.14-9 - Hyperlink bug?

Going form http://localhost:8754/index.html -> Show tracked aircraft list

You will get a list of tracked flight. Some of them will have the callsign as hyperlinked. But if you click on it, it will return as:

403 Forbidden

I looked at the URL and compared with the website - turns out it's missing a slash at the end of the URL, i.e

Not working:

Question: Is it a bug with this feeder software (forgot the slash to be added to html code) or is the website of flightradar24 set up incorrectly?