Using a the "unit" number formatting throws an exception

[simonjodet]

vue & vue-i18n version

ex: 2.6.10, 8.15.0

Reproduction Link

https://jsfiddle.net/qghvs0Lc/

Steps to reproduce

Use any unit style when formatting a number

What is Expected?

The number to be formatted.

What is actually happening?

An exception is thrown. The reason is that "unit" is not included numberFormatKeysand thus the unit option is stripped resulting in the exception below:

    at new NumberFormat (<anonymous>)
    at VueI18n._n (vue-i18n.js:1839)
    at VueI18n.n (vue-i18n.js:1895)
    at Proxy.eval (eval at createFunction (vue.js:11628), <anonymous>:1:69)
    at Vue._render (vue.js:3545)
    at Vue.updateComponent (vue.js:4061)
    at Watcher.get (vue.js:4472)
    at new Watcher (vue.js:4461)
    at mountComponent (vue.js:4068)
    at Vue.$mount (vue.js:9038)```

[simonjodet]

Thanks!