const NodeCache = require('node-cache');

const cacheSsr = new NodeCache({
  stdTTL: 5,
  checkperiod: 0,
});

module.exports = cacheSsr;

export class SsrCache {
  private _cache: any;

  constructor() {
    this._cache = require('./cacheSsr');
  }

  get(key) {
    const cacheSsr = this._cache;

    return cacheSsr.get(key);
  }
}

import { SsrCache } from './ssrHelper';

const ssrCache = new SsrCache();

const cachedData = ssrCache.get('key');

TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at NodeCache._getValLength (webpack:///./node_modules/node-cache/lib/node_cache.js?:690:56)
    at NodeCache.del (webpack:///./node_modules/node-cache/lib/node_cache.js?:461:38)
    at NodeCache._check (webpack:///./node_modules/node-cache/lib/node_cache.js?:600:18)
    at NodeCache.get (webpack:///./node_modules/node-cache/lib/node_cache.js?:332:46)
    at SsrCache.get