[xstate/vue] useMachine(machine) with no second parameter causes errors

[Glutnix]

Description

useMachine requires a second parameter to be at least an empty object, while documentation says it is optional

Expected Result

useMachine(toggleMachine) to work as documented

Actual Result

useMachine throws a type error when it tries to spread the second parameter when it's undefined.

Reproduction

https://codesandbox.io/s/xsharp-vue-usemachine-second-param-f5bpk?expanddevtools=1&fontsize=14&hidenavigation=1&module=%2Fsrc%2FApp.vue

Specifically App.vue:21 breaks it. Line 23 is the work around.

Additional context

Additionally, the documentation here:

https://xstate.js.org/docs/packages/xstate-vue/ does not match the documentation here: https://github.com/davidkpiano/xstate/tree/master/packages/xstate-vue specifically, the former link references current while the package and its documentation have moved to using state

 "dependencies": {
    "@vue/cli-plugin-babel": "4.1.1",
    "@vue/composition-api": "0.3.4",
    "@xstate/vue": "0.1.0",
    "vue": "^2.6.11",
    "xstate": "4.7.7"
  },

[davidkpiano]

Thank you for the repro! I'll take a look at this 🔜