You're sort of on the right track if you're familiar with URL/percent encoding, actually. I have no idea why, but paraphrased comments by the podcast hosts from

You're sort of on the right track if you're familiar with URL/percent encoding, actually. I have no idea why, but paraphrased comments by the podcast hosts from the code author (they contacted him) suggest that he was attempting to decode all incoming strings as if they were percent encoded[0] without any failsafes in place. Since "% I" isn't a valid character reference (or even hexadecimal), it chokes on it. [0]: https://datatracker.ietf.org/doc/html/rfc3986#section-2.1 https://datatracker.ietf.org/doc/html/rfc3986#section-2.1