Issue #3512179: Check for documented optional 'type' key before accessing.
https://www.drupal.org/project/drupal/issues/3512179#comment-16198860
Present behavior emits a warning for an undefined array key "type" and continues to return the string type. This is maintained. The documentation states you can leave the "type" key undefined if you have an exclusively DB specific type eg. "mysql_type"
Closes #3512179