Fix lock issue

Author: keelerm84

ldclient/impl/datasystem/store.py

@@ -92,6 +92,8 @@ def set_basis(self, collections: Collections):
         Initializes the store with a full set of data, replacing any existing data.
         """
         try:
+            self._lock.lock()
+
             all_decoded = {}
             for kind in collections:
                 collection = collections[kind]
@@ -100,7 +102,6 @@ def set_basis(self, collections: Collections):
                     items_decoded[key] = kind.decode(collection[key])
                 all_decoded[kind] = items_decoded
 
-            self._lock.lock()
             self._items.clear()
             self._items.update(all_decoded)
             self._initialized = True