Make media storage optional

If generating the SelectedMediaStorage configuration results in an
error (because there is no MediaUrl or Bunny CDN is not configured)
then don't configure the `/media` end-point, and make sure that the
`/micropub?q=config` query does not return a media-endpoint URL.

config.go

@@ -87,7 +87,7 @@ func initConfig() (err error) {
 		return nil
 	}()
 	if SelectedMediaStorage == nil {
-		return errors.New("no media storage configured")
+		log.Println("no media storage configured")
 	}
 	// Find selected CDN (optional)
 	SelectedCdn = func() Cdn {

main.go

@@ -17,7 +17,9 @@ func main() {
 	log.Println("Blog URL: " + BlogUrl)
 	log.Println("Ignored URLs for Webmention: " + strings.Join(IgnoredWebmentionUrls, ", "))
 	http.HandleFunc("/micropub", HandleMicroPub)
+	if SelectedMediaStorage != nil {
 		http.HandleFunc("/media", HandleMedia)
+	}
 	http.HandleFunc("/webmention", HandleWebmention)
 	log.Fatal(http.ListenAndServe(":5555", nil))
 }

mediaendpoint.go

@@ -11,6 +11,11 @@ import (
 )
 
 func HandleMedia(w http.ResponseWriter, r *http.Request) {
+	if SelectedMediaStorage == nil {
+		// This shouldn't happen since the HTTP handler isn't set up if there is no SelectedMediaStorage
+		w.WriteHeader(http.StatusNotFound)
+		_, _ = w.Write([]byte("No media endpoint configured"))
+	}
 	if r.Method != "POST" {
 		w.WriteHeader(http.StatusMethodNotAllowed)
 		_, _ = w.Write([]byte("The HTTP method is not allowed, make a POST request"))

micropub.go

@@ -12,6 +12,14 @@ type MicropubConfig struct {
 	MediaEndpoint string              `json:"media-endpoint,omitempty"`
 }
 
+func getMediaEndpoint() string {
+	if SelectedMediaStorage != nil {
+		return MediaEndpointUrl
+	} else {
+		return ""
+	}
+}
+
 func HandleMicroPub(w http.ResponseWriter, r *http.Request) {
 	// a handler for GET requests, used for troubleshooting
 	if r.Method == "GET" {
@@ -20,7 +28,7 @@ func HandleMicroPub(w http.ResponseWriter, r *http.Request) {
 			w.WriteHeader(http.StatusOK)
 			jsonBytes, err := json.Marshal(&MicropubConfig{
 				SyndicateTo:   SyndicationTargets,
-				MediaEndpoint: MediaEndpointUrl,
+				MediaEndpoint: getMediaEndpoint(),
 			})
 			if err != nil {
 				w.WriteHeader(http.StatusBadRequest)