added assertion to check object length in _convert_from_saved_type

Author: voith

frontera/contrib/backends/remote/codecs/json.py

@@ -43,8 +43,8 @@ def _convert_from_saved_type(obj):
     the second value to be the converted value. It applies the original type
     recursively on the object to retrieve the original form of the object.
     """
-    obj_type = obj[0]
-    obj_value = obj[1]
+    assert len(obj) == 2
+    obj_type, obj_value = obj
     if obj_type == 'bytes':
         return to_bytes(obj_value)
     elif obj_type == 'dict':