网页可以显示，但是compile结束后console里报错：

[Vue warn]: Error in mounted hook: "TypeError: _msg_js__WEBPACK_IMPORTED_MODULE_0___default.a.$on is not a function"

found in

---> <Right> at src/components/Right.vue

       <First> at src/views/First.vue

         <App> at src/App.vue

           <Root>

TypeError: _msg_js__WEBPACK_IMPORTED_MODULE_0___default.a.$on is not a function

    at VueComponent.mounted (Right.vue?df38:17)

    at invokeWithErrorHandling (vue.runtime.esm.js?2b0e:1854)

    at callHook (vue.runtime.esm.js?2b0e:4213)

    at Object.insert (vue.runtime.esm.js?2b0e:3139)

    at invokeInsertHook (vue.runtime.esm.js?2b0e:6340)

    at Vue.patch [as __patch__] (vue.runtime.esm.js?2b0e:6559)

    at Vue._update (vue.runtime.esm.js?2b0e:3939)

    at Vue.updateComponent (vue.runtime.esm.js?2b0e:4060)

    at Watcher.get (vue.runtime.esm.js?2b0e:4473)

    at new Watcher (vue.runtime.esm.js?2b0e:4462)

点击菜单后报错

[Vue warn]: Error in v-on handler: "TypeError: _msg_js__WEBPACK_IMPORTED_MODULE_0___default.a.$emit is not a function"

found in

---> <Left> at src/components/Left.vue

       <First> at src/views/First.vue

         <App> at src/App.vue

           <Root>

TypeError: _msg_js__WEBPACK_IMPORTED_MODULE_0___default.a.$emit is not a function

    at VueComponent.menu1 (Left.vue?162a:25)

    at invokeWithErrorHandling (vue.runtime.esm.js?2b0e:1854)

    at HTMLLIElement.invoker (vue.runtime.esm.js?2b0e:2179)

    at HTMLLIElement.original._wrapper (vue.runtime.esm.js?2b0e:6911)

Right.vue里kk的值也没有发生变化。求解