Cast ParameterExpression to float in RZXBuilder and RZXCalibrationBui…

…lderNoEcho (#8965) (#8994)

* committing changes but still debugging

* commiting to check necessary changes

* added explicit casting to get_calibration in rzx_builder.py in two places

* found a linting error in alap.py

* Remove redundant float cast

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
(cherry picked from commit de8e4dd)

Co-authored-by: nick bronn <ntbronn@us.ibm.com>

qiskit/transpiler/passes/calibration/rzx_builder.py

@@ -164,11 +164,17 @@ def get_calibration(self, node_op: CircuitInst, qubits: List) -> Union[Schedule,
             schedule: The calibration schedule for the RZXGate(theta).
 
         Raises:
+            QiskitError: if rotation angle is not assigned.
             QiskitError: If the control and target qubits cannot be identified.
             CalibrationNotAvailable: RZX schedule cannot be built for input node.
         """
         theta = node_op.params[0]
 
+        try:
+            theta = float(theta)
+        except TypeError as ex:
+            raise QiskitError("Target rotation angle is not assigned.") from ex
+
         rzx_theta = Schedule(name="rzx(%.3f)" % theta)
         rzx_theta.metadata["publisher"] = CalibrationPublisher.QISKIT
 
@@ -275,12 +281,18 @@ def get_calibration(self, node_op: CircuitInst, qubits: List) -> Union[Schedule,
             schedule: The calibration schedule for the RZXGate(theta).
 
         Raises:
+            QiskitError: if rotation angle is not assigned.
             QiskitError: If the control and target qubits cannot be identified,
                 or the backend does not natively support the specified direction of the cx.
             CalibrationNotAvailable: RZX schedule cannot be built for input node.
         """
         theta = node_op.params[0]
 
+        try:
+            theta = float(theta)
+        except TypeError as ex:
+            raise QiskitError("Target rotation angle is not assigned.") from ex
+
         rzx_theta = Schedule(name="rzx(%.3f)" % theta)
         rzx_theta.metadata["publisher"] = CalibrationPublisher.QISKIT