Querying the linear inputs of a QFree command throws an error.

[aborgna-q]

Test case:

let qb_row = vec![QB_T; 1];
let mut h = DFGBuilder::new(FunctionType::new(qb_row.clone(), vec![]))?;
let [q_in] = h.input_wires_arr();
h.add_dataflow_op(Tk2Op::QFree, [q_in])?;
let circ = h.finish_hugr_with_outputs([], &REGISTRY)?;

let mut cmds = circ.commands();
let free_cmd = cmds.next().unwrap();
assert_eq!(
    free_cmd.inputs().map(|(unit, _, _)| unit).collect_vec(),
    [CircuitUnit::Linear(0)]
);

Error:

thread 'circuit::command::test::alloc_free' panicked at tket2/src/circuit/command.rs:169:13:
Could not assign a linear unit to port Port(Incoming, 0) of node Node(3)