Return correct Content-Type for unrecognized requests (#3355)

Fixes #3354

Author: S7evinK

internal/httputil/routing.go

@@ -66,15 +66,15 @@ func NewRouters() Routers {
 }
 
 var NotAllowedHandler = WrapHandlerInCORS(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-	w.WriteHeader(http.StatusMethodNotAllowed)
 	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusMethodNotAllowed)
 	unrecognizedErr, _ := json.Marshal(spec.Unrecognized("Unrecognized request")) // nolint:misspell
 	_, _ = w.Write(unrecognizedErr)                                               // nolint:misspell
 }))
 
 var NotFoundCORSHandler = WrapHandlerInCORS(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-	w.WriteHeader(http.StatusNotFound)
 	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusNotFound)
 	unrecognizedErr, _ := json.Marshal(spec.Unrecognized("Unrecognized request")) // nolint:misspell
 	_, _ = w.Write(unrecognizedErr)                                               // nolint:misspell
 }))

internal/httputil/routing_test.go

@@ -17,7 +17,7 @@ func TestRoutersError(t *testing.T) {
 	if rec.Code != http.StatusNotFound {
 		t.Fatalf("unexpected status code: %d - %s", rec.Code, rec.Body.String())
 	}
-	if ct := rec.Header().Get("Content-Type"); ct != "application/json" {
+	if ct := rec.Result().Header.Get("Content-Type"); ct != "application/json" {
 		t.Fatalf("unexpected content-type: %s", ct)
 	}
 
@@ -32,7 +32,7 @@ func TestRoutersError(t *testing.T) {
 	if rec.Code != http.StatusMethodNotAllowed {
 		t.Fatalf("unexpected status code: %d - %s", rec.Code, rec.Body.String())
 	}
-	if ct := rec.Header().Get("Content-Type"); ct != "application/json" {
+	if ct := rec.Result().Header.Get("Content-Type"); ct != "application/json" {
 		t.Fatalf("unexpected content-type: %s", ct)
 	}
 }