Coming here from #366.
I have used this program some time ago and I noticed that the start script used invalid URLs to fetch the mapping and index files used by Gerbil. As a temporary fix, I suggest updating the script with Leipzig University links that work fine.
I haven't opened any PR that includes the updated links since I don't know if there is any copyright on it, but I can do it if that's okay with you.
Regards,
Leonardo Emili