What are the potential pitfalls of relying on setlocale() for language settings, especially when certain languages are missing?

When relying on setlocale() for language settings, one potential pitfall is that certain languages may be missing on the system, leading to unexpected behavior or errors. To mitigate this issue, it is recommended to check if the desired locale is available before setting it using setlocale().

$locale = 'fr_FR'; // Desired locale
if (in_array($locale, array_map('strtolower', explode(' ', setlocale(LC_ALL, 0))))) {
    setlocale(LC_ALL, $locale);
} else {
    // Handle missing locale error
    echo 'Error: Locale ' . $locale . ' is not available on this system.';
}