Undefined variable used in raise

[Randl]

Environment

Current master

What is happening?

Here
https://github.com/Qiskit/qiskit-terra/blob/5177db6e09917809895fe37878422ba8fcb6321a/qiskit/transpiler/passes/calibration/rzx_builder.py#L363
the variable cr_sched is undefined.

How can we reproduce the issue?

Call the function with wrong parameters

What should happen?

The exception should be raised

Any suggestions?

Change the description to not include undefined variable

[jakelishman]

Thanks for pointing this out! I imagine that the original intent was to say "native direction cannot be determined" and a bit of debugging information to go with it. Would you be interested in making a PR that updates the error to say that, and includes the qubits and instruction schedule map passed to the function?

[Randl]

Sure, I'll do that