src/Client/CurlHttpClient.php
private function checkClientError(ResponseInterface $response, RequestInterface $request)
    {
        if ($response->getStatusCode() >= 400 && $response->getStatusCode() < 500) {
            throw new ClientErrorException($request, $response);
        }
    }
private function checkClientError(ResponseInterface $response, RequestInterface $request)
    {
        if ($response->getStatusCode() >= 400 && $response->getStatusCode() < 500) {
            throw new ClientErrorException($request, $response);
        }
    }
Checks provided response is an HTTP client error (4xx)

@param ResponseInterface $response
@param RequestInterface $request

@throws ClientErrorException for responses with status codes between 400 and 499