"Error: Call to a member function getLanguages() on null" - when creating a redirect - no translations being used on the site...

Problem/Motivation

When creating a redirect we're getting this error in watchdog.

Error: Call to a member function getLanguages() on null in Drupal\redirect\Form\RedirectForm->form() (line 83 of /app/web/modules/contrib/redirect/src/Form/RedirectForm.php).

Which is the detail for the human error, "You are attempting to redirect the page to itself. This will result in an infinite loop."

This is an old site, that I inherited, so I don't know ALL of this history, but we are NOT translating content. But the LANGUAGE module is installed.

I've done all the checks I can find to see if the source path we're trying to use, exists, and it does not. I've even looked at the database in a raw text editor searching for the path... and its not there.

The code, mentioned in the error...

    // Only add the configured languages and a single key for all languages.
    if (isset($form['language']['widget'][0]['value'])) {
      foreach ($this->languageManager->getLanguages(LanguageInterface::STATE_CONFIGURABLE) as $langcode => $language) {    // <-- this is line 83, mentioned in the error
        $form['language']['widget'][0]['value']['#options'][$langcode] = $language->getName();
      }
      $form['language']['widget'][0]['value']['#options'][LanguageInterface::LANGCODE_NOT_SPECIFIED] = $this->t('- All languages -');
    }

Clearly is checking for a language setting of some kind, and I'm thinking that just having the language module installed (even though we're not using it) is causing a problem?

The language widget on the redirect is set to ALL LANGUAGES, and also gives the error if I set it to "English".
There are no other languages available on the site.

This client uses the redirect functionality WIDELY with this not being reported before (~20,000 nodes on this site, and 6159 rows in the redirect table in the DB...).

My ONLY guess, is that this being a very old node, in the 10,000 nid range, that maybe the language selection functionality was more complex, with other languages in the past... (before I took over the support of the site).... BUT, I also deleted ALL 173 revisions on this node... in my testing.

Thoughts?

Thanks.