Environment

• Qiskit version: 1.1, 1.2, and main
• Python version: Any
• Operating system: Linux

What is happening?

When running a large quantum volume circuit through the SabreLayout pass the individual trials start to internally panic with the following:

thread '<unnamed>' panicked at 'called `Option::unwrap()` on a `None` value', crates/accelerate/src/sabre/layer.rs:73:52

once for each thread launched. Once all 20 threads panic the pass stops.

How can we reproduce the issue?

from qiskit.circuit.library import QuantumVolume
import qiskit
from qiskit.transpiler import PassManager
from qiskit.transpiler.passes import SabreLayout, Unroll3qOrMore
from qiskit.transpiler import CouplingMap

qv = QuantumVolume(1000, seed=42)
qv.measure_all()
qc = Unroll3qOrMore()(qv)

cmap = CouplingMap.from_heavy_hex(21)
pm = PassManager([
    SabreLayout(cmap, swap_trials=20, layout_trials=20, max_iterations=4),
])

tqc = pm.run(qc)

What should happen?

The pass shouldn't panic, and should successfully apply a layout and route the circuit.

Any suggestions?

This was most likely a regression introduced by: #11977 as the example works fine with Qiskit 1.0.2.