我使用laravel-vue-i18 n-generator包在我的laravel项目中处理vuejs组件中的文本翻译。我设置了app.js如下：

import VueInternationalization from 'vue-i18n';
import Locale from './vue-i18n-locales.generated';

Vue.use(VueInternationalization);

const lang = 'fa';

const i18n = new VueInternationalization({
    locale: lang,
    messages: Locale
});

const app = new Vue({
    el: '#app',
    i18n,
});

在组件中：

<template>

    <a href="#" class="tip" title="" :title="$t('component.delete.title')" @click.prevent="deleteAction">
        <i :class="icon"></i>
    </a>
</template>

<script>
    import swal from 'sweetalert';
    import axios from 'axios';

    export default {
        inject: ['$i18n'],
        props:{
            endpoint: {
                type: String,
                required: true,
            },
            icon: {
                type: String,
                default: 'fa fa-trash'
            },
            message: {
                type: String,
                default:  this.$i18n.t('component.delete.are_you_sure'),
            },
            confirm: {
                type: String,
                default:  this.$i18n.t('component.delete.confirm'),
            },
            cancel: {
                type: String,
                default:  this.$i18n.t('component.delete.cancel'),
            },
            success: {
                type: String,
                default:  this.$i18n.t('component.delete.success'),
            },
            failed: {
                type: String,
                default:  this.$i18n.t('component.delete.failed'),
            },
        },
        mounted() {
            console.log(this);
        },
        methods:{
            deleteAction(){
                const vm = this;
                swal({
                    text: this.message,
                    buttons: {
                        catch: {
                            text: this.confirm,
                            value: "delete",
                        },
                        cancel: this.cancel
                    },
                    dangerMode: true
                }).then(name => {
                    if (!name) return false;

                    axios.delete(vm.endpoint)
                        .then(function (response) {
                            swal( vm.$i18n.t('component.delete.congrats'),vm.success, 'success').then(() => {
                                location.reload();
                            });
                        })
                        .catch(function (error) {
                            swal( vm.$i18n.t('component.delete.error'), vm.failed, 'error');
                        });
                });
            }
        }

    }
</script>

<style scoped>

</style>

幸运的是，$t('component.delete.title')在模板部分可以正常工作，但在脚本部分，我得到了这个错误：
未捕获的类型错误：无法读取未定义的属性“t”
我哪里做错了？