Update src/braket/circuits/result_type.py

src/braket/circuits/result_type.py

@@ -209,7 +209,7 @@ def __init__(
         super().__init__(ascii_symbols)
         self._observable = observable
         self._target = QubitSet(target)
-        if target is not None:
+        if self._target:
             if isinstance(observable, Sum):  # nested target
                 if len(target) != len(observable.summands):
                     raise ValueError(