fix regression from recent refactor that causes infinite loop on unexpected disconnect

libs/esl/src/esl.c

@@ -1231,8 +1231,9 @@ static esl_ssize_t handle_recv(esl_handle_t *handle, void *data, esl_size_t data
 			if ((activity & ESL_POLL_ERROR)) {
 				activity = -1;
 			} else if ((activity & ESL_POLL_READ)) {
-				activity = recv(handle->sock, data, datalen, 0);
-				if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) {
+				if (!(activity = recv(handle->sock, data, datalen, 0))) {
+					activity = -1;
+				} else if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) {
 					activity = 0;
 				}
 			}