Prop 'mode' set on national crashes nuxt

[olinox14]

I'm working on a nuxt application which is running on docker.
If I add the prop mode="national" in my tag, the page crash and the following
message appears in the console:

TypeError: _vm.activeCountry.iso2 is undefined
    fn vue-tel-input-vuetify.vue:42
    normalized VueJS

My tag looks like this:

 <vue-tel-input-vuetify
    field="phone"
    :label="$t('phone')"
    :value="entry['phone']"
    :preferredCountries="['FR', 'DE', 'CH', 'BE', 'GB']"
    :invalidMsg="$t('phoneInvalid')"
    mode="national"
  />

An expected behavior could be a fallback in international mode when an error occured with the national mode.

Libraries:

vuex-orm/core": "1.0.0-draft.14
nuxt: 2.15
nuxtjs/vuetify: 1.12.1,
vue-tel-input-vuetify: 1.4.1

Environment: Docker, debian based container

UPDATE

If I'm not mistaken, the error comes from the line 27 of vue-tel-input-vuetify.vue:

<div :class="activeCountry.iso2.toLowerCase()" class="vti__flag" />