[client] ds: validate the ds before attempting to use it

client/src/main.c

@@ -633,6 +633,7 @@ static int lg_run(void)
     }
 
   assert(g_state.ds);
+  assert(IS_LG_DS_VALID(g_state.ds));
 
   // init the subsystem
   if (!g_state.ds->earlyInit())