Fix qpy for controlled UnitaryGate

qiskit/qpy/binary_io/circuits.py

@@ -150,8 +150,9 @@ def _loads_instruction_parameter(type_key, data_bytes, version, vectors, registe
     elif type_key == type_keys.Value.REGISTER:
         param = _loads_register_param(data_bytes.decode(common.ENCODE), circuit, registers)
     else:
+        clbits = circuit.clbits if circuit is not None else ()
         param = value.loads_value(
-            type_key, data_bytes, version, vectors, clbits=circuit.clbits, cregs=registers["c"]
+            type_key, data_bytes, version, vectors, clbits=clbits, cregs=registers["c"]
         )
 
     return param

releasenotes/notes/fix-qpy-controlled-unitary-26355d6ffa4cd2fb.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixed a bug in QPY serialization (:mod:`qiskit.qpy`) where controlled unitary gates in
+    a circuit could result would fail to deserialize.  Fixed `#10802
+    <https://github.com/Qiskit/qiskit-terra/issues/10802>`__.

test/python/circuit/test_circuit_load_from_qpy.py

@@ -169,6 +169,20 @@ def test_unitary_gate(self):
         self.assertEqual(qc, new_circ)
         self.assertDeprecatedBitProperties(qc, new_circ)
 
+    def test_controlled_unitary_gate(self):
+        """Test that numpy array parameters are correctly serialized
+        in controlled unitary gate."""
+        qc = QuantumCircuit(2)
+        unitary = np.array([[0, 1], [1, 0]])
+        gate = UnitaryGate(unitary)
+        qc.append(gate.control(1), [0, 1])
+        with io.BytesIO() as qpy_file:
+            dump(qc, qpy_file)
+            qpy_file.seek(0)
+            new_circ = load(qpy_file)[0]
+        self.assertEqual(qc.decompose(reps=6), new_circ.decompose(reps=6))
+        self.assertDeprecatedBitProperties(qc, new_circ)
+
     def test_opaque_gate(self):
         """Test that custom opaque gate is correctly serialized"""
         custom_gate = Gate("black_box", 1, [])