Firebase trying to return onAuthStateChanged - firebase

Question

Trying to implement firebase authentication, the login, sign in, logout are working so trying to return if user is logged in or not.
The userID from my store is returning as undefined/not updating when trying to display it.
When checking in vue dev tools the userId never changes.
It is not logging as an error in my console just as undefined. in a single line with a grey textcolor
<template>
<div>
<button #click="log"></button>
</div>
</template>
<script>
import firebase from 'firebase'
import { mapState } from 'vuex'
export default {
name: 'Navigation',
data () {
return {
}
},
computed: {
...mapState({
userId: state => state.userId
})
},
methods: {
loggedOut() {
this.$store.dispatch('logout')
},
log() {
console.log(this.$store.userId)
}
}
}
</script>
^this is my vue file
import Vue from 'vue'
import Vuex from 'vuex'
import db from '../firebase'
import router from '../router';
// import firebase from '../firebase'
import firebase from 'firebase'
//https://github.com/robinvdvleuten/vuex-persistedstate
Vue.use(Vuex)
import createPersistedState from "vuex-persistedstate"
export const store = new Vuex.Store({
plugins: [createPersistedState()],
state: {
userId: ''
},
mutations: {
LOGOUT(state, userId) {
state.userId = '';
},
SET_USER_ID(state, userId) {
state.userId = userId;
}
},
actions: {
checkUserStatus({ commit, state }) {
return new Promise((resolve, reject) => {
firebase.auth().onAuthStateChanged((user) => {
if (user) {
commit('SET_USER_ID', user.uid);
resolve(user.uid);
} else {
reject('User is not logged in.');
}
})
})
},
signIn(context, credentials) {
firebase.auth().createUserWithEmailAndPassword(credentials.username, credentials.password)
.then(data => {
router.push('/')
alert('Signed in!')
})
.catch(e => {
alert(e.message)
})
},
login(context, credentials) {
firebase.auth().signInWithEmailAndPassword(credentials.username, credentials.password)
.then(data => {
router.push('/')
alert('Logged inn')
})
.catch(e => {
console.log(e, ' Loggin failed')
alert(e.message)
})
},
logout(context) {
firebase.auth().signOut()
.then(data => {
router.push('/Login')
alert('logged out')
})
.catch(e => {
alert(e.message)
})
},
...
}
})
export default store