FIX: return and empty dict for type stability

databroker/v1.py

@@ -67,6 +67,7 @@ def root_map(self):
  "details are handled for you on the server side, so you should not worry "
  "about this message unless you encounter trouble loading large array data."
  )
+ return {}
 
  def register_handler(self, *args, **kwargs):
  warnings.warn(