how to capture/ignore client-cancel-request error in buffer middleware

[onestraw]

When I use buffer and reverseproxy to handle failover, I found that buffer can not handle the case that reverseproxy.go return 502 if client canceled the request (maybe the connection has gone).

Currently, as I have remove the strict check for expectBody, buffer return 500 at here

If I ignore this specific case, buffer received 502 from reverseproxy, it will attempt to resend the request.

My question is that is there any method to identify client-cancel-request error and gracefully ignored it (not logged 502/500 error)?