remove assert and add logs when response received after request flushed

[dinesh-murugiah]

In production we have seen scenarios where the response is received while there was no pending request tied to it
this could happen in very corner cases of race condition , where a connection close event and the response handling is triggered at the same time
The work arround is to remove the assert and replace it with error logs to see what response is received and adding variables to check if it was followed by request flushing

[pratheep-kumar]

LG