报错了，问下是什么原因啊？Property or method "session" is not defined on the instance but referenced during render

[luki2678511]

chunk.js:2519 [Vue warn]: Property or method "session" 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

---> <Message> at D:\simu_idea\simu800-chat\simu800-chat-web\src\components\message.vue <App> at D:\simu_idea\simu800-chat\simu800-chat-web\src\page\main\App.vue <Root>