How to use the @grpc/grpc-js.status.UNKNOWN function in @grpc/grpc-js

it('should return true for retryable errors', () => {
      [
        status.OK,
        status.CANCELLED,
        status.UNKNOWN,
        status.DEADLINE_EXCEEDED,
        status.RESOURCE_EXHAUSTED,
        status.ABORTED,
        status.INTERNAL,
        status.UNAVAILABLE,
        status.DATA_LOSS,
      ].forEach((code: status) => {
        const shouldRetry = retrier.retry({code} as StatusObject);
        assert.strictEqual(shouldRetry, true);
      });
    });

our probe here the likely cause of this is that we are connecting to an lnd node where the `noseedbackup`
           flag has been set and therefore the `WalletUnlocker` interace is non-functional.

           https://github.com/grpc/grpc-node/blob/master/packages/grpc-native-core/src/constants.js#L129.
         */
        case status.UNIMPLEMENTED:
        case status.DEADLINE_EXCEEDED:
          debug('Determined wallet state as:', WALLET_STATE_ACTIVE)
          walletState = WALLET_STATE_ACTIVE
          return walletState

        /**
          `UNKNOWN` indicates that unlockWallet was called without an argument which is invalid.
          This implies that the wallet is waiting to be unlocked.
        */
        case status.UNKNOWN:
          debug('Determined wallet state as:', WALLET_STATE_LOCKED)
          walletState = WALLET_STATE_LOCKED
          return walletState

        /**
          Bubble all other errors back to the caller and abort the connection attempt.
          Disconnect all services.
        */
        default:
          console.error(error)
          debug('Unable to determine wallet state', error)
          throw error
      }
    } finally {
      if (!options.keepalive && this.can('disconnect')) {
        await this.disconnect()

  sendError (error, code = Status.UNKNOWN) {
    const { status } = this;

    if ('message' in error) {
      status.details = error.message;
    } else {
      status.details = 'Unknown Error';
    }

    if ('code' in error && Number.isInteger(error.code)) {
      status.code = error.code;

      if ('details' in error && typeof error.details === 'string') {
        status.details = error.details;
      }
    } else {
      status.code = code;

*
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import {StatusObject, status} from '@grpc/grpc-js';

/*!
 * retryable status codes
 */
export const RETRY_CODES: status[] = [
  status.OK,
  status.CANCELLED,
  status.UNKNOWN,
  status.DEADLINE_EXCEEDED,
  status.RESOURCE_EXHAUSTED,
  status.ABORTED,
  status.INTERNAL,
  status.UNAVAILABLE,
  status.DATA_LOSS,
];

/**
 * Used to track pull requests and determine if additional requests should be
 * made, etc.
 *
 * @class
 * @private
 */
export class PullRetry {

constructor(err: Error) {
    super(
      `Failed to connect to channel. Reason: ${
        process.env.DEBUG_GRPC ? err.stack : err.message
      }`
    );
    this.code = err.message.includes('deadline')
      ? status.DEADLINE_EXCEEDED
      : status.UNKNOWN;
    this.details = err.message;
    this.metadata = new Metadata();
  }
}