Whoa sorry for that!
I cannot reproduce that :(

Can you elaborate on:

• node version
• webpack setup
• typescript setup

please?

package.json:

{
  "name": "tmp.VHDDkc0A",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "node-cache": "^5.0.0"
  }
}

index.js:

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

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

class SsrCache {
  constructor() {
    this._cache = cacheSsr;
  }

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

    return cacheSsr.get(key);
  }
}

const ssrCache = new SsrCache();
const cached = ssrCache.get("key");

Hi @erdii and thanks for answering.

• node version is v10.13.0
• webpack setup:

const webpack = require('webpack');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const ServerMiniCssExtractPlugin = require("./server/utils/serverMiniCssExtractPlugin");
const LoadablePlugin = require('@loadable/webpack-plugin');

const getCssLoader = (localIdentName, localsConvention) => ({
  loader: 'css-loader',
  options: {
    modules: {
      localIdentName,
    },
    localsConvention,
    sourceMap: true,
  }
});
const sassLoader = 'sass-loader';
const postcssLoader = 'postcss-loader';

module.exports = [{
  name: 'react-app',
  mode: 'development',
  devtool: 'eval',
  cache: true,
  entry: {
    main: [
      'babel-polyfill',
      'webpack-hot-middleware/client?reload=true',
      './react/index.tsx',
    ],
  },
  output: {
    path: `${__dirname}/dist/__build__`,
    filename: '[name].js',
    chunkFilename: '[name].[hash].js',
    publicPath: '/__build__/',
  },
  module: {
    rules: [{
      test: /\.(ts|js)x?$/,
      loader: 'babel-loader',
      exclude: [/node_modules/],
    }, {
      test: /\.scss$/,
      oneOf: [{
        resourceQuery: /^\?raw$/,
        use: [
          MiniCssExtractPlugin.loader,
          getCssLoader('[local]', 'asIs'),
          sassLoader,
          postcssLoader
        ],
      }, {
        use: [
          MiniCssExtractPlugin.loader,
          getCssLoader('[path]___[name]__[local]___[hash:base64:5]', 'camelCaseOnly'),
          sassLoader,
          postcssLoader
        ],
      }]
    }],
  },
  resolve: {
    extensions: ['.ts', '.tsx', '.js'],
  },
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
    new webpack.NamedModulesPlugin(),
    new webpack.DefinePlugin({
      'process.env': {
        CLIENT: JSON.stringify(true),
        ENV: JSON.stringify(process.env.ENV)
      },
    }),
    new webpack.IgnorePlugin(/^vertx$/),
    new MiniCssExtractPlugin({
      filename: "style.css",
      chunkFilename: "style.chunk.css"
    })
  ],
  optimization: {
    splitChunks: {
      cacheGroups: {
        vendor: {
          test: /node_modules/,
          name: 'vendor',
          enforce: true
        },
        style: {
          test: /\.scss$/,
          name: 'style',
          enforce: true
        },
      },
    },
  },
}, {
  name: 'server-side rendering',
  mode: 'development',
  devtool: 'eval',
  cache: true,
  entry: [
    './react/ssr.tsx',
  ],
  target: 'node',
  output: {
    path: `${__dirname}/dist/__server__/`,
    filename: 'ssr.js',
    publicPath: '/__server__/',
    libraryTarget: 'commonjs2',
  },
  resolve: {
    extensions: ['.ts', '.tsx', '.js'],
  },
  module: {
    rules: [{
      test: /\.(ts|js)x?$/,
      exclude: [/node_modules/, /.+\.config.js/],
      loader: 'babel-loader',
    }, {
      test: /\.scss$/,
      oneOf: [{
        resourceQuery: /^\?raw$/,
        use: [
          ServerMiniCssExtractPlugin.loader,
          getCssLoader('[local]', 'asIs'),
          sassLoader,
          postcssLoader
        ],
      }, {
        use: [
          ServerMiniCssExtractPlugin.loader,
          getCssLoader('[path]___[name]__[local]___[hash:base64:5]', 'camelCaseOnly'),
          sassLoader,
          postcssLoader
        ],
      }]
    }],
  },
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
    new webpack.NamedModulesPlugin(),
    new webpack.DefinePlugin({
      'process.env': {
        SERVER: JSON.stringify(true),
        ENV: JSON.stringify(process.env.ENV)
      },
    }),
    new webpack.IgnorePlugin(/^vertx$/),
    new ServerMiniCssExtractPlugin({
      filename: "style.css",
      chunkFilename: "style.chunk.[id].css"
    }),
    new LoadablePlugin()
  ],
}];

• typescript setup (tsconfig.json):

{
  "compilerOptions": {
      "outDir": "./dist/__build__/",
      "sourceMap": true,
      "noImplicitAny": true,
      "module": "esnext",
      "target": "es5",
      "types": ["jest", "node"],
      "lib": ["es2015", "es2019", "dom"],
      "jsx": "react",
      "moduleResolution": "node",
      "experimentalDecorators": true,
      "esModuleInterop": true,
      "baseUrl": ".",
      "paths": {
        "*": ["./react/@types/*"]
      }
  },
  "include": [
      "./react/**/*.tsx",
      "./react/**/*.ts",
      "./tests/jestsetup.ts",
      "./tests/react/**/*.tsx"
  ]
}

forgot to tell, the error is happening in the server-side rendering of the application, don't know if I disable the SSR

hm... I feared, that you would try to use node-cache in the browser, but it's dependency on the internal "events" module should make that impossible.

But you tried on the server-side and node_modules are excluded from webpack in your config... that should work

Can you maybe show me the generated parts of your code?

I get a similar error when trying to set to null, Node 10.16.3. No webpack, no typescript, node-cache@5.0.0, clone@2.1.2:

$ cat test.js 
'use strict';

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

try {
  cache.set('test', null);
} catch (err) {
  console.error(err);
}
$ node test.js 
TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at NodeCache._getValLength (/run/user/1000/test/node_modules/node-cache/lib/node_cache.js:690:56)
    at NodeCache.set (/run/user/1000/test/node_modules/node-cache/lib/node_cache.js:402:34)
    at Object.<anonymous> (/run/user/1000/test/test.js:6:9)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)
$ node --version
v10.16.3
$ 

The problem disappears if I change line 688 of lib/node_cache.js from:

} else if (typeof value === "object") {

to:

} else if (value !== null && typeof value === "object") {

I also have this problem.
It's not longer possible to set null to a key.
Or rather it's possible but throws the error (it still worked)
Once something was set null it will no longer be able to be reset.

Example:

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

cache.get(1) // undefined
cache.set(1, null) // throws an error
cache.get(1) // now null
cache.set(1, 'this is valid') // also throws an error
cache.get(1) // still null

Fixed the bug in #152, tests are still running. I'll merge this as soon as they finished and then I'll create a patch release.

Thank you all for debugging and reporting this!

v5.0.1 has been released! Thank you again and sorry for the inconvenience :)

Thank you for the quick fix, and for node-cache!