Forgetting the return after replying to an HTTP request

Mistake

func handler(w http.ResponseWriter, req *http.Request) {
  err := foo(req)
  if err != nil {
    // this doesn't stop the function
    http.Error(w, "foo", http.StatusInternalServerError)
  }

  // ...
}

Fix

func handler(w http.ResponseWriter, req *http.Request) {
  err := foo(req)
  if err != nil {
    http.Error(w, "foo", http.StatusInternalServerError)
    return
  }

  // ...
}

References