Uncaught TypeError: Class extends value undefined is not a constructor or null

[wolfomat]

Using the example provided here, i've got this message. Code:

Uncaught TypeError: Class extends value undefined is not a constructor or null

import * as tillhub from '@tillhub/javascript-sdk'

// configure which API to use. E.g. you can also run staging and sandbox APIs
th.init({
  base: 'https://api.tillhub.com'
})

// use any authentication method that .auth provides
th.auth.loginUsername({ username: 'xxxxxxxx@xxxxxx.com', password: 'xxxxxxx' })

I'm using this in <script setup> tag in vue js.
Should be running there, i guess, or is there another way?

Same when adding the code to main.js