MessageSource.php
public function init()
    {
        parent::init();
        $this->translator = Instance::ensure($this->translator, 'conquer\i18n\TranslatorInterface');
        if ($this->enableCaching) {
            $this->cache = Instance::ensure($this->cache, Cache::className());
        }        
    }
public function init()
    {
        parent::init();
        $this->translator = Instance::ensure($this->translator, 'conquer\i18n\TranslatorInterface');
        if ($this->enableCaching) {
            $this->cache = Instance::ensure($this->cache, Cache::className());
        }        
    }
Initializes the DbMessageSource component.
This method will initialize the [[db]] property to make sure it refers to a valid DB connection.
Configured [[cache]] component would also be initialized.
@throws InvalidConfigException if [[db]] is invalid or [[cache]] is invalid.