update error message on auth failure

[v9n]

Fixes #46

auth key resp

  code: 16,
  details: 'User authentication error: User Auth key is invalid',
  metadata: Metadata {
    internalRepr: Map(1) { 'content-type' => [ 'application/grpc' ] },
    options: {}
  }
}

api key resp

    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async main (/Users/vinh/Sites/oak/eigenlayer/EigenLayer-AVS/examples/example.js:271:28) {
  code: 16,
  details: 'User authentication error: API key is invalid',
  metadata: Metadata {
    internalRepr: Map(1) { 'content-type' => [ 'application/grpc' ] },
    options: {}
  }
}

[chrisli30]

Nice 👍