ThemePicker::getDefaultTheme

public function getDefaultTheme()
{
	$theme = null;

	$res = ThemeTable::getList([
		'filter' => [
			'=ENTITY_TYPE' => $this->getEntityType(),
			'ENTITY_ID' => 0,
			'=CONTEXT' => $this->getContext(),
		],
		'select' => [ 'THEME_ID', 'USER_ID' ],
		'cache' => static::getSelectCacheParams(),
	]);

	if ($themeFields = $res->fetch())
	{
		if ($this->isCustomThemeId($themeFields['THEME_ID']))
		{
			$theme = $this->getCustomTheme($themeFields['THEME_ID'], $themeFields['USER_ID']);
		}
		else
		{
			$theme = $this->getStandardTheme($themeFields['THEME_ID']);
		}
	}

	return $theme ?: $this->getStandardTheme(self::DEFAULT_THEME_ID);
}