JSON helper for PHP

Helper.php

<?php

namespace \Json

class Helper
{
    /**
     * @var array
     */
    protected $errorReference = [
        JSON_ERROR_NONE => 'No error has occurred.',
        JSON_ERROR_DEPTH => 'The maximum stack depth has been exceeded.',
        JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON.',
        JSON_ERROR_CTRL_CHAR => 'Control character error, possibly incorrectly encoded.',
        JSON_ERROR_SYNTAX => 'Syntax error.',
        JSON_ERROR_UTF8 => 'Malformed UTF-8 characters, possibly incorrectly encoded.',
        // These last 3 messages are only supported on PHP >= 5.5.
        // See http://php.net/json_last_error#refsect1-function.json-last-error-returnvalues
        JSON_ERROR_RECURSION => 'One or more recursive references in the value to be encoded.',
        JSON_ERROR_INF_OR_NAN => 'One or more NAN or INF values in the value to be encoded.',
        JSON_ERROR_UNSUPPORTED_TYPE => 'A value of a type that cannot be encoded was given.',
    ];
    /**
     * @var string
     */
    const JSON_UNKNOWN_ERROR = 'Unknown error.';

    /**
     * Provides the error message, related to json_last_error().
     *
     * If the error code is not found, returns a default `Unknown error` message.
     *
     * @param int $errorCode Return from json_last_error()
     *
     * @return string The error message.
     */
    public static function getLastErrorMessage($errorCode)
    {
        if (!array_key_exists($errorCode, $this->errorReference)) {
            return self::JSON_UNKNOWN_ERROR;
        }

        return $this->errorReference[$errorCode];
    }
}