Handle empty response bodies correctly

lib/liudesk_cmdb/client.rb

@@ -80,7 +80,7 @@ module LiudeskCMDB
       response.body
     rescue Net::HTTPClientException, Net::HTTPFatalError
       begin
-        body = JSON.parse(response.body)
+        body = JSON.parse(response.body) unless response.body.empty?
       rescue StandardError => e
         logger.debug "Failed to parse error response - #{e.class}: #{e}"
         body = response.body