Qiskit statevector simulator returns wrong result when skipping classical bits.

Hi!

I noticed that when "skipping" a classical bit, meaning not measuring to some bit $x$ but to bit $y$ with $ind(x) < ind(y)$, the cusvaer-enabled statevector simulator returns the wrong result, simply ignoring the result on bit $y$. This does not happen when not enabling cusvaer.

See the example below:

from qiskit.circuit import QuantumCircuit
from qiskit_aer import Aer

sim = Aer.get_backend("aer_simulator_statevector")
sim.set_option("cusvaer_enable", True)

circuit = QuantumCircuit(4, 5)
circuit.h(0)
circuit.cx(range(3), range(1, 4))
circuit.measure([0, 1, 2, 3], [0, 1, 2, 4])

print(circuit)

wrong_result = sim.run(circuit, shots=10000).result().get_counts()
print("Wrong:", wrong_result)

sim.set_option("cusvaer_enable", False)

correct_result = sim.run(circuit, shots=10000).result().get_counts()
print("Correct:", correct_result)

     ┌───┐          ┌─┐              
q_0: ┤ H ├──■───────┤M├──────────────
     └───┘┌─┴─┐     └╥┘     ┌─┐      
q_1: ─────┤ X ├──■───╫──────┤M├──────
          └───┘┌─┴─┐ ║      └╥┘┌─┐   
q_2: ──────────┤ X ├─╫───■───╫─┤M├───
               └───┘ ║ ┌─┴─┐ ║ └╥┘┌─┐
q_3: ────────────────╫─┤ X ├─╫──╫─┤M├
                     ║ └───┘ ║  ║ └╥┘
c: 5/════════════════╩═══════╩══╩══╩═
                     0       1  2  4 
Wrong: {'00000': 4993, '00111': 5007}
Correct: {'10111': 5026, '00000': 4974}

I suspect there might be some missing bookkeeping of the indices of classical registers in the cusvaer backend.

Thanks!
Nate