upgrade_oniro: add error handling for restore

Add error handling for restore in case the backup is not found.

Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>

scripts/upgrade_oniro/upgrade_oniro.py

@@ -185,11 +185,16 @@ def restore_oniro():
 
     if backup_archive_arg == "latest":
         backup_archive_name = find_latest_backup()
-
-    if os.path.exists(backup_archive_arg):
+        if backup_archive_name is None:
+            print("No backup found, aborting...")
+            return
+    elif os.path.exists(backup_archive_arg):
         # TODO add a check to be sure that the selected path is actually a Oniro backup
         backup_archive_name = backup_archive_arg
-    
+    else:
+        print(f"'{backup_archive_arg}' has not been found, aborting...")
+        return
+
     print(f"Restoring {backup_archive_name}")
     with tarfile.open(backup_archive_name) as backup_archive:
         # Extract the metadata file and delete all the old folders