[Error] Next14 - invariant expected app router to be mounted, The above error occurred in the <HotReload> component

Uncaught Error: invariant expected app router to be mounted

The above error occurred in the <HotReload> component:

두 에러가 떴다

 

해결

layout.js에 html은 있는데, body태그를 삭제해서 일어난 에러
html태그와 body태그가 필수로 있어야함