Non-deterministic behavior of npm

After running npm install, I have noticed that sometimes package-lock.json changes.

This section:

  "dependencies": {
    "websocket": {
      "version": "git://github.com/frozeman/WebSocket-Node.git#6c72925e3f8aaaea8dc8450f97627e85263999f2",
      "from": "git://github.com/frozeman/WebSocket-Node.git#6c72925e3f8aaaea8dc8450f97627e85263999f2",
      "requires": {
        "debug": "^2.2.0",
        "nan": "^2.3.3",
        "typedarray-to-buffer": "^3.1.2",
        "yaeti": "^0.0.6"
      }
    }
  }
}

Changes to this:

  "dependencies": {
    "websocket": {
      "version": "git://github.com/frozeman/WebSocket-Node.git#6c72925e3f8aaaea8dc8450f97627e85263999f2",
      "from": "git://github.com/frozeman/WebSocket-Node.git#6c72925e3f8aaaea8dc8450f97627e85263999f2",
      "requires": {
        "debug": "^2.2.0",
        "nan": "^2.3.3"
      }
    }
  }
}

And when that happens, I get a runtime error:

module.js:538
    throw err;
    ^

Error: Cannot find module 'typedarray-to-buffer'
    at Function.Module._resolveFilename (module.js:536:15)
    at Function.Module._load (module.js:466:25)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (C:\Users\...\node_modules\web3-providers-ws\node_modules\websocket\lib\W3CWebSocket.js:18:16)
    at Module._compile (module.js:635:30)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)

After some debugging, this error is for require("web3") in my code.

Here is the relevant section in my package.json file:

  "devDependencies": {
    "chai": "^4.1.2",
    "chai-as-promised": "^7.0.0",
    "bignumber.js": "^7.0.0",
    "decimal.js": "^10.0.0",
    "web3": "1.0.0-beta.34",
    "ethereumjs-testrpc-sc": "6.1.2",
    "ganache-cli": "6.1.0",
    "solidity-coverage": "0.4.14",
    "truffle": "4.1.3"
  }

Can anyone please advise how I may resolve this, and why npm works differently from time to time?

Thank you.