update docstring

Author: anon

qubesadmin/base.py

@@ -285,6 +285,9 @@ def _parse_type_value(self, prop_type: bytes, value: bytes) -> VMProperty:
         Parse `type=... ...` qubesd response format. Return a value of
         appropriate type.
 
+        Returns AttributeError instead of ValueError since this used
+        to access named field <prop_type>
+
         :param bytes prop_type: 'type=...' part of the response (including
             `type=` prefix)
         :param bytes value: 'value' part of the response