Client initialisation could end before client is actually ready

[gnarea]

I should be doing something like the following in init():

    const client = new CogRPCClient(`${address.host}:${address.port}`, credentials);
    await new Promise((resolve, reject) => {
      client.grpcClient.waitForReady(makeDeadline(), (error) => {
        if (error) {
          reject(error);
        } else {
          resolve();
        }
      });
    });
    return client;