Remove undefined variable

qiskit/transpiler/passes/calibration/rzx_builder.py

@@ -360,7 +360,10 @@ def _check_calibration_type(
         cr_sched = inst_sched_map.get("ecr", tuple(reversed(qubits)))
         cal_type = CRCalType.ECR_REVERSE
     else:
-        raise QiskitError(f"{repr(cr_sched)} native direction cannot be determined.")
+        raise QiskitError(
+            f"Native direction cannot be determined: operation on qubits {qubits} "
+            f"for the following instruction schedule map:\n{inst_sched_map}"
+        )
 
     cr_tones = [t[1] for t in filter_instructions(cr_sched, [_filter_cr_tone]).instructions]
     comp_tones = [t[1] for t in filter_instructions(cr_sched, [_filter_comp_tone]).instructions]

releasenotes/notes/fix-exception-decription-3ba0b5db82c576cf.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - Fix a bug in :class:`~.RZXCalibrationBuilder` where calling calibration with wrong parameters
+    would crash instead of raising exception.

test/python/transpiler/test_calibrationbuilder.py

@@ -16,10 +16,12 @@
 
 import numpy as np
 from ddt import data, ddt
+from qiskit.converters import circuit_to_dag
 
-from qiskit import circuit, schedule
+from qiskit import circuit, schedule, QiskitError
 from qiskit.circuit.library.standard_gates import SXGate, RZGate
 from qiskit.providers.fake_provider import FakeHanoi  # TODO - include FakeHanoiV2, FakeSherbrooke
+from qiskit.providers.fake_provider import FakeArmonk
 from qiskit.pulse import (
     ControlChannel,
     DriveChannel,
@@ -247,6 +249,24 @@ def test_rzx_calibration_rotary_pulse_stretch(self, theta: float):
             test_sched.duration, self.compute_stretch_duration(self.d1p_play(cr_schedule), theta)
         )
 
+    def test_raise(self):
+        """Test that the correct error is raised."""
+        theta = np.pi / 4
+
+        qc = circuit.QuantumCircuit(2)
+        qc.rzx(theta, 0, 1)
+        dag = circuit_to_dag(qc)
+
+        backend = FakeArmonk()
+        inst_map = backend.defaults().instruction_schedule_map
+        _pass = RZXCalibrationBuilder(inst_map)
+
+        qubit_map = {qubit: i for i, qubit in enumerate(dag.qubits)}
+        with self.assertRaises(QiskitError):
+            for node in dag.gate_nodes():
+                qubits = [qubit_map[q] for q in node.qargs]
+                _pass.get_calibration(node.op, qubits)
+
     def test_ecr_cx_forward(self):
         """Test that correct pulse sequence is generated for native CR pair."""
         # Sufficiently large angle to avoid minimum duration, i.e. amplitude rescaling