Property or method "show" is not defined on the instance but referenced during render

[weituotian]

vue.esm.js?e6fa:571 [Vue warn]: Property or method "show" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.

found in

---> <Loading> at src\components\Loading.vue
       <App> at src\App.vue
         <Root>