private fun check_response(uri: String, response: CurlResponse): nullable String do
		if response isa CurlResponseSuccess then
			was_error = false
			return response.body_str
		else if response isa CurlResponseFailed then
			last_error = new GithubAPIError(
				response.error_msg,
				response.error_code,
				uri
			)
			was_error = true
			return null
		else abort
	end