Vue3 Pinia Store cannot access 'store" before initializsation - vue.js

Question

I have a UserStore which contains some information about the current user. This store also is responsible for loggin in and out.
In order to make the getters available I map the getters to my computed attribute within my Vue component.
Unfortunately I get an error saying that it cannot access useUserStore before initilization.
This is my component:
<template>
//...
</template>
<script>
import {mapState} from "pinia"
import {useUserStore} from "../../stores/UserStore.js";
import LoginForm from "../../components/forms/LoginForm.vue";
export default {
name: "Login",
components: {LoginForm},
computed: {
...mapState(useUserStore, ["user", "isAuthenticated"]) //commenting this out makes it work
}
}
</script>
This is my store:
import { defineStore } from 'pinia'
import {gameApi} from "../plugins/gameApi.js"
import {router} from "../router.js";
export const useUserStore = defineStore("UserStore", {
persist: true,
state: () => ({
authenticated: false,
_user: null
}),
getters: {
user: (state) => state._user,
isAuthenticated: (state) => state.authenticated
},
actions: {
async checkLoginState() {
// ...
},
async loginUser(fields) {
// ...
},
async logutUser() {
// ...
}
}
})
And my main.js
import {createApp} from 'vue'
import App from './App.vue'
import gameApi from './plugins/gameApi'
import {router} from './router.js'
import store from "./stores/index.js";
createApp(App)
.use(store)
.use(router)
.use(gameApi)
.mount('#app')
And finally my store configuration:
import {createPinia} from "pinia"
import piniaPluginPersistedstate from 'pinia-plugin-persistedstate'
import {useUserStore} from "./UserStore.js";
const piniaStore = createPinia()
piniaStore.use(piniaPluginPersistedstate)
export default {
install: (app, options) => {
app.use(piniaStore)
const userStore = useUserStore()
const gameStore = useGameStore()
}
}

Answer 1

I wasn't able to initialize the store using the "old" way comparable with Vuex. Instead I had to make use of the setup() function Pinia Docu:
<script>
import {useUserStore} from "../../stores/UserStore.js";
export default {
name: "RegisterForm",
setup() {
// initialize the store
const userStore = useUserStore()
return {userStore}
},
data() {
return {
// ...
}
},
methods: {
checkLoginState() {
this.userStore.checkLoginState()
}
}
}
</script>