decode json from file_get_contents(); ,with error displaying

json-decode.php

function decodeJson($json, $assoc = false)
{
    $json = preg_replace('/[\x00-\x1F\x7F]/u', '', $json);
    $ret = json_decode($json, $assoc);
    if ($error = json_last_error()) {
        $errorReference = [
            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.',
            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.',
        ];
        $errStr = isset($errorReference[$error]) ? $errorReference[$error] : "Unknown error ($error)";
        throw new \Exception("JSON decode error ($error): $errStr");
    }
    return $ret;
}