Nuxt-auth custom refresh controller

Our backend refresh API needs 2 parameters: the grant_type & the refresh_token. The nuxt-auth v5 does support refresh token but the default handleRefresh() does not allow custom parameters as far as I can see – if this can be tweaked, that would also be great.

As a workaround, I tried creating a custom scheme + custom refresh controller. This is my code until now:

// nuxt.config.js

auth: {
  strategies: {
    local: {
      scheme: '~/schemes/refresh_token.js',
      token: {
        property: 'token',
        global: true,
        type: 'Bearer'
      },
      refreshToken: {
        property: 'refresh_token',
        data: 'refresh_token',
        maxAge: 60 * 60 * 24 * 30
      },
      endpoints: {
        login: { url: '/api/v1/login', method: 'post', propertyName: 'data.token' },
        user: { url: '/api/v1/profile', method: 'get', propertyName: '' },
        refresh: { url: '/api/v1/token', method: 'post' }
      }
    }
  }
}

// schemes/refresh_token.js

import { RefreshScheme } from '@nuxtjs/auth-next';
import RefreshTokenController from './controllers/refresh_token';

export default class RefreshTokenScheme extends RefreshScheme {
  constructor ($auth, options) {
    super($auth, options);
    this.refreshController = new RefreshTokenController(this);
  }
}

// schemes/controllers/refresh_token.js

import { RefreshController } from "@nuxtjs/auth-next";

export default class RefreshTokenController extends RefreshController {
  handleRefresh() {
    console.log('custom handle refresh');
  }
}

Right now, I have this error:
Class extends value undefined is not a constructor or null at the export default class RefreshTokenController extends RefreshController line.

Also, my console says:
This dependency was not found: * fs in ./node_modules/@nuxtjs/auth-next/dist/module.js, ./node_modules/hasha/index.js