framework/web/ErrorHandler.php
public function getExceptionName($exception)
    {
        if ($exception instanceof \yii\base\Exception || $exception instanceof \yii\base\InvalidCallException || $exception instanceof \yii\base\InvalidParamException || $exception instanceof \yii\base\UnknownMethodException) {
            return $exception->getName();
        }

        return null;
    }
public function getExceptionName($exception)
    {
        if ($exception instanceof \yii\base\Exception || $exception instanceof \yii\base\InvalidCallException || $exception instanceof \yii\base\InvalidParamException || $exception instanceof \yii\base\UnknownMethodException) {
            return $exception->getName();
        }

        return null;
    }
Returns human-readable exception name.
@param \Exception $exception
@return string human-readable exception name or null if it cannot be determined