Testing Angular4 app with autobahn gives "TypeError: Cannot read property 'unmask' of undefined"

Question

I've stumbled upon some other related topics, but all seem resolved in a way that's not helping me. My autobahn package config (the relevant parts at least):

"version": "17.5.2",
  "description": "An implementation of The Web Application Messaging Protocol (WAMP).",
  "main": "index.js",
  "scripts": {
    "test": "nodeunit test/test.js"
  },
  "engines": {
    "node": ">= 4.2.6"
  },
  "dependencies": {
    "crypto-js": ">= 3.1.8",
    "int64-buffer": ">= 0.1.9",
    "msgpack-lite": ">= 0.1.26",
    "cbor": ">= 3.0.0",
    "tweetnacl": ">= 0.14.3",
    "when": ">= 3.7.7",
    "ws": ">= 1.1.4"
  },
  "optionalDependencies": {
    "bufferutil": ">= 1.2.1",
    "utf-8-validate": ">= 1.2.1"
  },

As you can see, the ws package is in proper version, the same goes for bufferutil, so what gives?