htmlspecialchars() expects parameter 1 to be string, array given

[extensibleseth]

In message_subscribe_email.module, array_keys($uids) returns an array. Adding another implode should fix it.

$debug && \Drupal::logger('message_subscribe_email')->debug(
'Gathering email subscriptions using flags: @flags for users: @uids',
['@flags' => implode(', ', $flag_ids), '@uids' => implode(', ', array_keys($uids))]
);