mint doesn't work

I follow the instructions here: https://github.com/bcnmy/sdk-examples/blob/modular-sdk-v3/backend-node/README.md

running
```
yarn run smartAccount mint
```
gets as a result:
```
error received { code: -32501, message: 'AA34 signature error' }
```

Start with backend-node/README.md and reproduce the documented `yarn run smartAccount mint` command. Investigate the reported `AA34 signature error` in the example's mint flow; done means the command completes successfully without that error.

Written by the indexing model from the issue text.