modules_k/uac In case uuid was not found in the case of remore registration, do not crash when jumping to label

modules_k/uac/uac_reg.c

@@ -628,7 +628,7 @@ void uac_reg_tm_callback( struct cell *t, int type, struct tmcb_params *ps)
 	}
 
 done:
-	ri->flags &= ~UAC_REG_ONGOING;
+	if(ri) ri->flags &= ~UAC_REG_ONGOING;
 	shm_free(uuid);
 }