Fix potential segmentation fault (SIGSEGV) error
Fix potential segmentation fault (SIGSEGV) error

The server->clients variable may still holds reference to user data which is already freed after websocket connection closed.

hosiet/ttyd,tsl0922/ttyd,tsl0922/ttyd,hosiet/ttyd,hosiet/ttyd,tsl0922/ttyd,hosiet/ttyd,tsl0922/ttyd,tsl0922/ttyd