Webmozart\Json\JsonDecoder::decodeJson PHP Method

    private function decodeJson($json)
    {
        $assoc = self::ASSOC_ARRAY === $this->objectDecoding;
        if (PHP_VERSION_ID >= 50400 && !defined('JSON_C_VERSION')) {
            $options = self::STRING === $this->bigIntDecoding ? JSON_BIGINT_AS_STRING : 0;
            $decoded = json_decode($json, $assoc, $this->maxDepth, $options);
        } else {
            $decoded = json_decode($json, $assoc, $this->maxDepth);
        }
        // Data could not be decoded
        if (null === $decoded && 'null' !== $json) {
            $parser = new JsonParser();
            $e = $parser->lint($json);
            if ($e instanceof ParsingException) {
                throw new DecodingFailedException(sprintf('The JSON data could not be decoded: %s.', $e->getMessage()), 0, $e);
            }
            // $e is null if json_decode() failed, but the linter did not find
            // any problems. Happens for example when the max depth is exceeded.
            throw new DecodingFailedException(sprintf('The JSON data could not be decoded: %s.', JsonError::getLastErrorMessage()), json_last_error());
        }
        return $decoded;
    }