Error in zyx-phpmailer extension for yii2, why?

Question

Yii

Installed extension zyx-phpmailer for yii 2.0.6

"require": {
        "php": ">=5.4.0",
        "yiisoft/yii2": ">=2.0.5",
        "yiisoft/yii2-bootstrap": "*",
        "zyx/zyx-phpmailer": "@stable"
    },

It was done as per the instructions, when sending I received a similar error . Which the author corrected, as it were, back in 2014.
So far, he made the function call static and sending works. Maybe someone faced this problem.

Answer 1

@stable

It is worth specifying the version explicitly.