updateLocale is not defined

[kalnode]

This Moment plugin works in my Nuxt app, however I'm attempting to customize labels for .fromNow() to be shorter. To do this many people recommend making use of custom locale's, like below.

Fails:

When using .fromNow( updateLocale(...

I get an error:

updateLocale is not defined

Works:
When using .fromNow() as is, there's no issue, however there's no point as no customization occurs!

Vue template:

{{ getDateFrom(conv.lastMessage.editedAt ? conv.lastMessage.editedAt : conv.lastMessage.createdAt) }}

Custom function:

getDateFrom(givenDate) {
            return this.$moment(givenDate)
            .fromNow(
                updateLocale("en", {
                    relativeTime: {
                        future: "in %s",
                        past: "%s ",
                        s: "sec",
                        m: "%d m",
                        mm: "%d m",
                        h: "%d h",
                        hh: "%d h",
                        d: "%d d",
                        dd: "%d d",
                        M: "a mth",
                        MM: "%d mths",
                        y: "y",
                        yy: "%d y"
                    }
                })
            )
        }