'Division by zero' in subscriptions.install upon updating

What? The dividend comes from

  db_result(db_query('SELECT MAX(uid) FROM {users}'))

and it gives you 0? You're running a site with no users, not even an administrator?

If you have, say, 1000 users, then you should have seen a progress bar with 20 browser reloads, processing 50 users at a time. At which point did this occur, at the beginning or at the end of this process?

subscriptions_update_7() is modeled one-to-one after system_update_172(). I could try an other termination condition, but I need to understand why it failed.

Here's the relevant source code:

function subscriptions_update_7() {
  if (!isset($_SESSION['subscriptions_update_7'])) {
    $_SESSION['subscriptions_update_7'] = 0;
    $_SESSION['subscriptions_update_7_max'] = db_result(db_query('SELECT MAX(uid) FROM {users}'));
  }

  $limit = 50;

  $result = db_query_range("SELECT uid FROM {users} WHERE uid > %d ORDER BY uid ASC", $_SESSION['subscriptions_update_7'], 0, $limit);
  while ($usr = db_fetch_object($result)) {
    // process this user...
    $_SESSION['subscriptions_update_7'] = $usr->uid;
  }

  if ($_SESSION['subscriptions_update_7'] == $_SESSION['subscriptions_update_7_max']) {
    unset($_SESSION['subscriptions_update_7']);
    unset($_SESSION['subscriptions_update_7_max']);
    return array();
  }
  return array('#finished' => $_SESSION['subscriptions_update_7'] / $_SESSION['subscriptions_update_7_max']);
}

Does anyone see how this can fail with a zero-divide exception on the last line?

BTW, you can restart subscriptions_update_7() any number of times without risking any problems.

This was an odd issue that no one else seems to have had. I'm sorry I wasn't able to provide more help...