Приветствие на разных языках на JavaScript

function greet(language) {

    let countries = {
        english: 'Welcome',
        czech: 'Vitejte',
        danish: 'Velkomst',
        dutch: 'Welkom',
        estonian: 'Tere tulemast',
        finnish: 'Tervetuloa',
        flemish: 'Welgekomen',
        french: 'Bienvenue',
        german: 'Willkommen',
        irish: 'Failte',
        italian: 'Benvenuto',
        latvian: 'Gaidits',
        lithuanian: 'Laukiamas',
        polish: 'Witamy',
        spanish: 'Bienvenido',
        swedish: 'Valkommen',
        welsh: 'Croeso'
    };

    for (let key in countries) {
        if (key === language) {
            return countries[key]
        }
    }
    if (language === 'IP_ADDRESS_INVALID' || 'IP_ADDRESS_NOT_FOUND' || 'IP_ADDRESS_REQUIRED'){
        return 'Welcome'
    }
    if (language === '') {
        return 'Welcome'
    }
}