feature(backups): check restore exit code

selfprivacy_api/backup/backuppers/restic_backupper.py

@@ -219,7 +219,7 @@ class ResticBackupper(AbstractBackupper):
             raise ValueError("cannot restore without knowing where to!")
 
         with tempfile.TemporaryDirectory() as dir:
-            self.do_restore(snapshot_id, target=dir)
+            self.do_restore(snapshot_id, target=dir, verify=verify)
             for folder in folders:
                 src = join(dir, folder.strip("/"))
                 if not exists(src):
@@ -249,6 +249,14 @@ class ResticBackupper(AbstractBackupper):
             if "restoring" not in output:
                 raise ValueError("cannot restore a snapshot: " + output)
 
+            assert (
+                handle.returncode is not None
+            )  # none should be impossible after communicate
+            if handle.returncode != 0:
+                raise ValueError(
+                    "restore exited with errorcode", returncode, ":", output
+                )
+
     def _load_snapshots(self) -> object:
         """
         Load list of snapshots from repository