TypeError: Argument #2 ($string) must be of type Drupal\babel\Model\StringTranslation, int given

Somehow, in BabelService, in

foreach ($rows as $row) {
      // Pickup the first key from $ids as the source string and context.
      [$key] = explode(',', $row->keys, 2);
      [$pluginId, $id] = explode(':', $key, 2);

      $byPlugin[$pluginId][$id] = $row->keys;
      $status[$row->keys] = $row->status;
    }

we are getting a locale: which results in an empty ID and the array_flip at the end of \Drupal\babel\BabelService::getStrings is causing it to be an integer - it tries to merge it with the $list but since there is no relevant match with locale:, it just retains the index as a value).

It seems like the culprit is because I can see in the babel_source table locale strings that do not have an ID

| plugin | id | status | hash | sort_key                  |
| locale |       | 1          | abcd | Announcements: |

Cannot reproduce. I'm going to close this issue. If you feel I'm wrong please reopen.