Error in "Repeat until success" tutorial

[frankharkins]

The following code cell raises an error. It's not clear this ever worked.

sampler = Sampler(backend)
job = sampler.run([isa_circuit])

simulator_counts = job.result()[0]
print(f">>> Simulator counts for mid: {simulator_counts.data.mid.get_counts()}")
print(f">>> Simulator counts for final: {simulator_counts.data.final.get_counts()}")

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[8], line 1
----> 1 sampler = Sampler(backend)
      2 job = sampler.run([isa_circuit])
      4 simulator_counts = job.result()[0]

File /usr/local/lib/python3.11/site-packages/qiskit_ibm_runtime/sampler.py:92, in SamplerV2.__init__(self, backend, session, options)
     90 BaseSamplerV2.__init__(self)
     91 Sampler.__init__(self)
---> 92 BasePrimitiveV2.__init__(self, backend=backend, session=session, options=options)
     94 if self._service._channel_strategy == "q-ctrl":
     95     raise NotImplementedError("SamplerV2 is not supported with q-ctrl channel strategy.")

File /usr/local/lib/python3.11/site-packages/qiskit_ibm_runtime/base_primitive.py:121, in BasePrimitiveV2.__init__(self, backend, session, options)
    115 self._service = (
    116     QiskitRuntimeService()
    117     if QiskitRuntimeService.global_service is None
    118     else QiskitRuntimeService.global_service
    119 )
    120 if self._service.channel != "ibm_cloud":
--> 121     raise ValueError(
    122         "A backend or session must be specified when not using ibm_cloud channel."
    123     )

ValueError: A backend or session must be specified when not using ibm_cloud channel.

[frankharkins]

This notebook just executed fine in https://github.com/Qiskit/documentation/actions/runs/9094865913/job/24996841295 🤔

[frankharkins]

It seems to only be a problem with the mock backend. I've marked it as "unmockable" in #1391. This is fine for now as its future is uncertain (see #1309). If we do revamp the notebook, we can look into this then.