ReferenceError: axios is not defined

I'm getting this error when I try to submit a form using vue

ReferenceError: axios is not defined

I don't know why this is happening. Isn't axios already imported in the bootstrap.js that's in the resources/js/ folder?

Here is my vue file

<template>
    <div class="container">
        <div class="row justify-content-center">
            <div class="col-md-8">
                <div class="card">
                    <div class="card-header">Example Component</div>

                    <div class="card-body">
                        I'm an Supplier Code Selection component.
                        <br>
                        
                        <form @submit.prevent="submit">
                            <label for="parent-product">Parent Product</label>
                            <select name="parent-product" id="parent-product" class="form-control" v-model="selected_parent">
                                <option>Please select your code</option>
                                <option v-for="product in products" :value="product.id">
                                    {{ product.supplier_code }}
                                </option>

                                    <option v-for="child in children" :value="child.id">
                                        {{ child.supplier_code }}
                                    </option>
                            </select>

                            <input type="submit" class="btn btn-primary" value="Submit">
                        </form>
                    </div>
                </div>
            </div>
        </div>
    </div>
</template>

<script>
    export default {
        props: [
            'products',
            'children',
            'selected_parent'
        ],

        mounted() {
            console.log('Component mounted.')
        },

        methods: {
            submit(){
                var formData = new FormData();

                console.log('this is the select box - '+this.selected_parent);
                formData.append('parent-product', this.selected_parent);

                return axios.post('/add-to-cart/'+this.selected_parent, formData);
            }
        },
    }
</script>