Error for invoke-snap example

I installed two snaps in https://github.com/MetaMask/snaps/tree/main/packages/examples/packages/invoke-snap and using the following code to revoke @metamask/consumer-signer-example-snap, but there is the same error as https://github.com/MetaMask/snaps/issues/2340 :

```
await window.ethereum.request({
method: 'wallet_requestSnaps',
params: {
'npm:@metamask/consumer-signer-example-snap': {},
},
});

const response = await window.ethereum.request({
method: 'wallet_invokeSnap',
params: {
snapId: 'npm:@metamask/consumer-signer-example-snap',
request: {
method: 'signMessage',
params: { message: 'test' },
},
},
});
```

Start in packages/examples/packages/invoke-snap and reproduce the wallet_requestSnaps and wallet_invokeSnap calls shown in the issue. Compare the failure with issue #2340 and inspect the example's Snap setup; done means the invoke-snap example no longer produces the reported error or clearly documents the remaining limitation.

Written by the indexing model from the issue text.