SwiftMailer not autoloaded
It appears that Swiftmailer is no longer autoloaded since the externaler swiftmailer/swiftmailer package is used.
Swiftmailer requires lib/swift_required.php to be executed - composer is able of doing this, according to the documentation Flow only supports PSR-0 autoloading.
Simply requiring swift_required.php when loading the package appears to be sufficient to fix this issue.
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