An alternate with an empty or malformed href is a broken link inside the signal that is supposed to hold the language versions together.
The finding reads:
warning hreflang-bad-code the “…” alternate has an empty href
Fix the language code: usually a country has been written where a language belongs.
Collapsed when it fires template-wide. If it appears on 90% or more of the pages — or of one language version — of a site with at least 20 pages, it is a property of the template and is reported once, with the count, instead of once per page.
pipx install indexgap
cd your-project
indexgap init
indexgap check
Then indexgap brief turns
every finding on this page into a work order in indexgap-briefs/,
with the thresholds the result has to satisfy and the command to check it.