Ошибка при валидации через vuelidate : Error in render: "TypeError: Cannot read property '$error' of undefined"

При валидации через vuelidate выходит ошибка - "app.js:42603 [Vue warn]: Error in render: "TypeError: Cannot read property '$error' of undefined" и "TypeError: Cannot read property '$error' of undefined". С чем может быть связана прооблема?

Код:

    <template>
    <div class="container">
        <h1>{{name}}</h1>
        <div class="form-group">
            <input type="text" @blur="saveName" v-model="name" class="form-control" :class="{ 'is-invalid': $v.name.$error }">
            <div class="invalid-feedback" v-if="!$v.name.required">
                Обязательное поле.
            </div>
            <div class="invalid-feedback" v-if="!$v.name.maxLength">
                Макс. колличество символов: {{$v.name.$params.maxLength.max}}
            </div>
        </div>
        <form @submit.prevent="addNewDeskList">
            <div class="form-group">
                <input type="text" v-model="desk_list_name" class="form-control" :class="{ 'is-invalid': $v.desk_list_name.$error }" placeholder="Введите название списка">
                <div class="invalid-feedback" v-if="!$v.desk_list_name.required">
                    Обязательное поле.
                </div>
                <div class="invalid-feedback" v-if="!$v.desk_list_name.maxLength">
                    Макс. колличество символов: {{$v.desk_list_name.$params.maxLength.max}}
                </div>
            </div>
            <button type="submit" class="btn btn-primary">Добавить список</button>
        </form>
        <div class="alert alert-danger" role="alert" v-if="errored">
            Ошибка загрузки данных!
        </div>
        <div class="row">
            <div class="col-lg-4" v-for="desk_list in desk_lists">
                <div class="card mt-3">
                    <div class="card-body" href="#">
                        <form @submit.prevent="updateDeskList(desk_list.id,desk_list.name)" v-if="desk_lists_input_id == desk_list.id" class="d-flex justify-content-between align-items-center">
                            <input type="text" v-model="desk_list.name" class="form-control" placeholder="Введите название списка">
                            <button @click="desk_lists_input_id = null" type="button" class="close" aria-label="Close">
                                <span aria-hidden="true">&times;</span>
                            </button>
                        </form>
                        <h4 v-else class="card-title d-flex justify-content-between align-items-center" style="cursor: pointer;" @click="desk_lists_input_id = desk_list.id">{{desk_list.name}}<i class="fas fa-pencil-alt" style="font-size: 15px;"></i></h4>
                        <button type="button" class="btn btn-danger mt-3" @click="deleteDeskList(desk_list.id)" >Удалить</button>
                        <div class="card mt-3 bg-light" v-for="card in desk_list.cards" :key="card.id">
                            <div class="card-body">
                                <h4 class="card-title d-flex justify-content-between align-items-center" style="cursor: pointer;">{{card.name}}</h4>
                                <button type="button" class="btn btn-secondary mt-3">Удалить</button>
                            </div>
                        </div>
                        <form @submit.prevent="addNewCard(desk_list.id)" class="mt-3">
                            <input type="text" v-model="card_names[desk_list.id]" :class="{'is-invalid': $v.card_names.$each[desk_list.id].$error}" class="form-control" placeholder="Введите название карточки" >
                            <div class="invalid-feedback" v-if="!$v.card_names.$each[desk_list.id].required">
                                Обязательное поле.
                            </div>
                            <div class="invalid-feedback" v-if="!$v.card_names.$each[desk_list.id].maxLength">
                                Макс. колличество символов: {{$v.card_names.$each[desk_list.id].$params.maxLength.max}}.
                            </div>
                        </form>
                    </div>
                </div>
            </div>
        </div>
        <div class="spinner-border" style="width: 4rem; height: 4rem;" role="status" v-if="loading">
            <span class="visually-hidden">Loading...</span>
        </div>
    </div>
</template>

<script>
import { required, maxLength } from 'vuelidate/lib/validators'
    export default {
        props: [
            'deskId'
        ],
        data() {
            return {
                errored: false,
                loading: true ,
                name: null,
                desk_list_name: null,
                desk_lists: null,
                desk_lists_input_id: null,
                card_names: [],
            }
        },
        methods: {
            addNewCard(desk_list_id) {
                this.$v.card_names.$each[desk_list_id].$touch()
                if(this.$v.card_names.$each[desk_list_id].$anyError) {
                    return;
                }

                axios.post('/api/V1/cards/', {
                    name: this.card_names[desk_list_id],
                    desk_list_id,
                })
                    .then(response => {
                        this.$v.card_names.$reset()
                        this.getDeskLists();
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
            },
            updateDeskList (id,name) {
                axios.post('/api/V1/desk-lists/'+id, {
                    _method:'PUT',
                    name
                })
                    .then(response => {
                        this.desk_lists_input_id = null
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })
            },
            deskUpdate() {
                axios.get('/api/V1/desk-lists', {
                    params: {
                        desk_id: this.deskId
                    }
                })
                    .then(response => {
                        this.desk_lists = response.data.data
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })

            },
            getDeskLists() {
                axios.get('/api/V1/desk-lists', {
                    params: {
                        desk_id: this.deskId
                    }
                })
                    .then(response => {
                        this.desk_lists = response.data.data
                        console.log(this.desk_lists)
                        debugger
                        this.desk_lists.forEach(el => {
                            this.card_names[el.id] = ''
                        })
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })
            },
            getDeskLists() {
                axios.get('/api/V1/desk-lists', {
                    params: {
                        desk_id: this.deskId
                    }
                })
                    .then(response => {
                        this.desk_lists = response.data.data
                        this.desk_lists.forEach(el => {
                            this.card_names[el.id] = ''
                        })
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })
            },
            saveName() {
                this.$v.name.$touch()
                if(this.$v.name.$anyError) {
                    return;
                }
                axios.post('/api/V1/desks/'+this.deskId, {
                    _method: 'PUT',
                    name: this.name,
                })
                    .then(response => {
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })
            },
            addNewDeskList() {
                this.$v.desk_list_name.$touch()
                if(this.$v.desk_list_name.$anyError) {
                    return;
                }
                axios.post('/api/V1/desk-lists', {
                    name: this.desk_list_name,
                    desk_id: this.deskId,
                })
                    .then(response => {
                        this.$v.desk_list_name.$reset()
                        this.desk_list_name = ''
                        this.desk_lists = []
                        this.getDeskLists()
                    })
                    .catch(error => {
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })
            },
            deleteDeskList(id) {
                axios.post('/api/V1/desk-lists/'+id, {
                    _method: 'DELETE',
                })
                    .then(response => {
                        this.desk_lists = []
                        this.getDeskLists()
                    })
                    .catch(error => {
                        console.log(error)
                        this.errored = true
                    })
                    .finally(() => {
                        this.loading = false
                    })
            },
        },
        mounted() {
            axios.get('/api/V1/desks/'+this.deskId)
                .then(response => {
                    this.name = response.data.data.name
                })
                .catch(error => {
                    console.log(error)
                    this.errored = true
                })
                .finally(() => {
                    this.loading = false
                })
            this.getDeskLists()
        },
        validations: {
            name: {
                required,
                maxLength: maxLength(5)
            },
            desk_list_name: {
                required,
                maxLength: maxLength(6)
            },
            card_names: {
                $each:{
                    required,
                    maxLength: maxLength(5)
                }
            }
        }
    }
</script>