$ headless-seo-check http://127.0.0.1:4311 --urls /hreflang-good,/hreflang-drift,/hreflang-dead,/hreflang-drift-dead,/hreflang-html-only --no-color
--- stdout+stderr ---
headless-seo-check: checking http://127.0.0.1:4311 …
headless-seo-check: 5 of 5 URLs selected, from --urls
headless-seo-check http://127.0.0.1:4311
  5 of 5 URLs checked, from --urls

  + /hreflang-good       static, 324 words
  x /hreflang-drift      static, 324 words
      error the Link: header and the HTML advertise different URLs for 1 language
            fr  header: http://127.0.0.1:4311/fr/hreflang-drift
            fr  HTML:   http://127.0.0.1:4311/fr/slug-traduit
            fr  the header target answers HTTP 200
  + /hreflang-dead       static, 327 words
  x /hreflang-drift-dead static, 327 words
      error the Link: header and the HTML advertise different URLs for 1 language
            fr  header: http://127.0.0.1:4311/fr/nexiste-pas
            fr  HTML:   http://127.0.0.1:4311/fr/slug-traduit
            fr  the header target does not exist (HTTP 404)
      error 1 hreflang target in the Link: header do not exist
            fr  http://127.0.0.1:4311/fr/nexiste-pas — does not exist (HTTP 404)
  + /hreflang-html-only  static, 325 words

  FAILED  3 blocking issues
     2 × hreflang-drift
     1 × hreflang-dead-target

  What to do
    hreflang-drift
      The Link: header and the HTML advertise different alternates for the same
      language, so the page has two sources of truth and one of them is wrong.
      Frameworks derive header alternates by swapping a locale prefix, which
      breaks the moment slugs are translated. Emit alternates in one place, not
      both.
    hreflang-dead-target
      An alternate points at a URL that does not exist. Google drops the whole
      hreflang cluster when one side is dead, so this costs you every language,
      not just the broken one. Fix the target or remove the alternate — an
      alternate that merely redirects is untidy, this one is not.

--- exit code: 1 ---