data: default to None

If the data is not set, it will raise an exception here. The stash key
may not be created if an exception occurs during modifyitems hook, which
now can happen if preferred_topology marker gets incorrect arguments.

Author: pbrezina

pytest_mh/_private/data.py

@@ -54,7 +54,7 @@ def SetData(item: pytest.Item, data: MultihostItemData | None) -> None:
 
     @staticmethod
     def GetData(item: pytest.Item) -> MultihostItemData | None:
-        return item.stash[DataStashKey]
+        return item.stash.get(DataStashKey, None)
 
 
 DataStashKey = pytest.StashKey[MultihostItemData | None]()