Fatal error: Uncaught Error: Class 'Yii' not found in /opt/lampp/htdocs/squidv2-stage-api/vendor copy/yiisoft/yii2-swiftmailer/tests/MailerTest.php:8 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/squidv2-stage-api/vendor copy/yiisoft/yii2-swiftmailer/tests/MailerTest.php on line 8