mod_websocket: Continue to process data already in the buffer after an error occurs

Previously any error, or even a normal websocket close frame, would return early,
leaving potentially entire frames in the buffer unprocessed and then discarded.

This change stops processing new data, but returns an existing processed data up
to the point of the error/close.

plugins/mod_websocket.lua

@@ -291,7 +291,7 @@ function handle_request(event)
 			end
 			frameBuffer:discard(length);
 			local result = handle_frame(frame);
-			if not result then return; end
+			if not result then break; end
 			cache[#cache+1] = filter_open_close(result);
 			frame, length = parse_frame(frameBuffer);
 		end