Proving key not initialized in NoirJS init

[signorecello]

Aim

I want to create a backend_barretenberg instance that only verifies, doesn't prove. Example code:

const backends = {
  alice: new BarretenbergBackend(main, {threads: 8}),
  bob: new BarretenbergBackend(main, {threads: 8})
}
const noirs = {
  alice: new Noir(main, backends.alice),
  bob: new Noir(main, backends.bob)
}
async function program() {
  const input = {x : 1, y: 2}
  const proof = await noirs.alice.generateFinalProof(input)
  await noirs.alice.verifyFinalProof(proof)
}

Expected Behavior

I expect the proof to verify

Bug

It doesn't verify, and the reason is because the proving key is not initialized on Bob's backend instance.

To Reproduce

Installation Method

None

Nargo Version

No response

Additional Context

No response

Would you like to submit a PR for this Issue?

Yes

Support Needs

No response