src/core/AppHelper.php
public function getConfig(string $sName = '')
    {
        if (empty($sName)) {
            return $this->configSet;
        } elseif (isset($this->configSet[$sName])) {
            return $this->configSet[$sName];
        } else {
            return null;
        }
    }
public function getConfig(string $sName = '')
    {
        if (empty($sName)) {
            return $this->configSet;
        } elseif (isset($this->configSet[$sName])) {
            return $this->configSet[$sName];
        } else {
            return null;
        }
    }
It returns the config value by passed name or all config set if it wasn't
specified.
@param string $sName The config name.
@return mixed|null