message: fix: fix client NPE
diff: import {EnvironmentUtil} from 'pandora-env';
  import {MockEnvironment} from './MockEnvironment';
  +import { MetricsClient, MetricsClientUtil } from 'pandora-metrics';
  const events = require('events');
  events.defaultMaxListeners = 100;
  process.env.NODE_ENV = 'test';
  // setup mock env
  EnvironmentUtil.getInstance().setCurrentEnvironment(new MockEnvironment());
  +MetricsClientUtil.setMetricsClient(MetricsClient.getInstance());
  