free(store) in renderd_list not safe for some storages

Some storages already have free(store) in close function. For example store_ro_composite.c:

static int ro_composite_close_storage(struct storage_backend * store) {
    struct ro_composite_ctx * ctx = (struct ro_composite_ctx *)(store->storage_ctx);
    ctx->store_primary->close_storage(ctx->store_primary);
    ctx->store_secondary->close_storage(ctx->store_secondary);
    if(ctx->cache.tile) free(ctx->cache.tile);
    free(ctx);
    free(store);
    return 0;
}

Here is the patch for renderd_list.c

--- a/src/render_list.c
+++ b/src/render_list.c
@@ -301,7 +301,9 @@ int main(int argc, char **argv)
     }

     store->close_storage(store);
-    free(store);
+    if (store != NULL) {
+        free(store);
+    }
     finish_workers();

     free(spath);

Start in src/render_list.c at the store->close_storage(store) call and the following free(store), then inspect close_storage implementations such as store_ro_composite.c. Confirm the ownership behavior across storage backends and verify that cleanup is safe for each one. Done means the change builds and no storage path frees the same store twice.