LoggerInterface::error() has unexpected side-effects in admin

[GuySartorelli]

Found while fixing silverstripe/silverstripe-framework#11034

If you log an error while saving a record, even though the record is successfully saved, the toast message turns red (as though it was a failure), and the form doesn't reload.

The toast message is unaffected - it's still the success message. The record still gets saved. The problem is specifically that the wrong type of toast is used, and the form doesn't reload.

Notes

• This was specifically tested using this code - it's not clear whether the specific .errorhandler service affects it, but probably not

  /** @var LoggerInterface $logger */
  $logger = Injector::inst()->get(LoggerInterface::class . '.errorhandler');
  $logger->error('Error sending email in ' . __FILE__ . ' line ' . __LINE__ . ": {$e->getMessage()}");

• using warning() instead of error() does not exhibit this buggy behaviour. It is specifically when logging an error that this occurs.