When trying to set a cookie with cookie-universal-nuxt in my router middleware I get the error:

TypeError: Cannot read properties of undefined (reading 'set')

What is causing this?

nuxt.config.js

modules: [
    'cookie-universal-nuxt',
],

router.js (router middleware)

export default async ({ app }) => {

    app.$cookies.set('cookie-name', 'cookie-value', {
        path: '/',
        maxAge: 60 * 60 * 24 * 7
    });
}

I tried logging in different places:

When I run console.log(app.$cookies) in the router it returns undefined.

When I run it in a component (so: console.log(this.app.$cookies)) it returns Cannot read properties of undefined (reading 'app'). I am using the composition-api so I also tried console.log(context.root.$cookies) but this also returns undefined.