framework/web/AssetManager.php
public function init()
    {
        parent::init();
        $this->basePath = Yii::getAlias($this->basePath);
        if (!is_dir($this->basePath)) {
            throw new InvalidConfigException("The directory does not exist: {$this->basePath}");
        }

        $this->basePath = realpath($this->basePath);
        $this->baseUrl = rtrim(Yii::getAlias($this->baseUrl), '/');
    }
public function init()
    {
        parent::init();
        $this->basePath = Yii::getAlias($this->basePath);
        if (!is_dir($this->basePath)) {
            throw new InvalidConfigException("The directory does not exist: {$this->basePath}");
        }

        $this->basePath = realpath($this->basePath);
        $this->baseUrl = rtrim(Yii::getAlias($this->baseUrl), '/');
    }
Initializes the component.
@throws InvalidConfigException if [[basePath]] does not exist.