src/includes/classes/Core/Utils/Utf8.php
public function isValid(string $string): bool
    {
        if (!isset($string[0])) {
            return true; // Nothing to do.
        }
        return (bool) preg_match('/^./us', $string);
    }
public function isValid(string $string): bool
    {
        if (!isset($string[0])) {
            return true; // Nothing to do.
        }
        return (bool) preg_match('/^./us', $string);
    }
Is valid UTF-8?

@since 150424 Enhancing multibyte support.

@param string $string Input string to test.

@return bool True if is valid UTF-8.