golang - Exit http handler from anywhere

I'm using the net/http package and wondering how I can exit the handler from anywhere in the code. Say I have this code:

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

func handler(w http.ResponseWriter, r *http.Request){
    err := checkSomeThing(w, r)

    if err != nil {
        return
    }

    fmt.Println("End of Handler.")
    return
}

func checkSomeThing(w http.ResponseWriter, r *http.Request) error{
    http.Error(w, "Bad Request!", http.StatusBadRequest) 
    
    return errors.New("bad request")
}

Ideally I'd like to exit the handler from within the checkSomeThing function without having to return and then return again up a level, which will get worse as the application grows. This is purely for code readability.

The idiomatic approach is to check error returns up the call chain.

To exit the the handler from anywhere, use panic and recover following the pattern in the encoding/json package.

Define a unique type for panic:

type httpError struct {
    status  int
    message string
}

Write a function to be used in a defer statement. The function checks for the type and handles the error as appropriate. Otherwise, the function continues the panic.

func handleExit(w http.ResponseWriter) {
    if r := recover(); r != nil {
        if he, ok := r.(httpError); ok {
            http.Error(w, he.message, he.status)
        } else {
            panic(r)
        }
    }
}

Write a helper function for the call to panic:

func exit(status int, message string) {
    panic(httpError{status: status, message: message})
}

Use the functions like this:

func example() {
   exit(http.StatusBadRequest, "Bad!")
}

func someHandler(w http.ResponseWriter, r *http.Request) {
   defer handleExit(w)
   example()
}