reflect.Value.Convert: value of type reflect.Value cannot be converted to type http.FileSystem

[your-olym]

I meet the question that

reflect.Value.Convert: value of type reflect.Value cannot be converted to type http.FileSystem 

which was seemd caused by

http.Handle("/js/", http.StripPrefix("/js/", http.FileServer(http.Dir("js"))))

by the way it's running in goland

├── static
│   └── js
│   └── index.js
├── templates
│   └── index.html