What is the problem?
On my local docker install of IPInfo, the infobox does not work. Instead, I get a javascript error:
TypeError: mw.storage is undefined.
According to @DLynch, the extension.json file is missing the dependency on mediawiki.storage.
For the production environment, this does not seem to make a difference as other extensions include mediawiki.storage instead.
However, if you install IPInfo in an environment where mediawiki.storage is not already being included by other extensions, the infobox won't work.