1. 开发环境报错Uncaught (in promise) TypeError: ‘set’ on proxy: trap returned falsish for property ‘$t’

legacy需要设置为false

const i18n = createI18n({
  legacy: false,
  // 默认语言
  locale: lang,
  // 设置语言环境
  messages,
})

2. 打包配置tsc --noEmit时报错：Type instantiation is excessively deep and possibly infinite

messages需要设置类型

import { I18nOptions } from 'vue-i18n';
 
const messages = {
  'zh-CN': { ...zhCN },
  'en-US': { ...enUS },
} as I18nOptions['messages'];

3.Uncaught (in promise) TypeError: _ctx.$t is not a function

$t需要全局注册, globalInjection设置为true

const i18n = createI18n({
  legacy: false,
  // 默认语言
  locale: lang,
  // 设置语言环境
  messages,
  globalInjection: true,
})