json parse error strings in PHP

json_error.php

<?php
class JSONErrorException extends \Exception {}
function json_error($error_code, $exceptionable = TRUE)
{
    static $json_errors = NULL;
    if ($json_errors === NULL)
    {
        $json_errors = [
            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',
        ];
        if (PHP_VERSION_ID >= 50303)
        {
            $json_errors = array_merge($json_errors, [
                JSON_ERROR_UTF8       => 'Malformed UTF-8 characters, possibly incorrectly encoded',
            ]);
        }
        if (PHP_VERSION_ID >= 50500)
        {
            $json_errors = array_merge($json_errors, [
                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',
            ]);
        }
        if (PHP_VERSION_ID >= 70000)
        {
            $json_errors = array_merge($json_errors, [
                JSON_ERROR_INVALID_PROPERTY_NAME => 'A property name that cannot be encoded was given',
                JSON_ERROR_UTF16                 => 'Malformed UTF-16 characters, possibly incorrectly encoded',
            ]);
        }
    }

    $error_code = (int)$error_code;
    $message = 'Unknown error code';
    if (isset($json_errors[$error_code]))
    {
        $message = $json_errors[$error_code];
    }
    if ($exceptionable && $error_code !== JSON_ERROR_NONE)
    {
        throw new JSONErrorException($message, $error_code);
    }
    return [$error_code, $message];
}

$json = "";
$obj = json_decode($json);
var_dump($obj);
print_r(json_error(json_last_error()));
// php 5.6.24
//
// NULL
// Array
// (
//     [0] => 0
//     [1] => No error has occurred
// )

// php 7.1.5
//
// NULL
// 
// Fatal error: Uncaught JSONErrorException: Syntax error in /path/to/path/json_error.php:46