Fix 404 being reported as 500.

src/pages.go

@@ -50,7 +50,6 @@ func getPage(w http.ResponseWriter, r *http.Request) error {
 	// if whatever we were serving doesn't exist, try to serve `$root/404.html`
 	if errors.Is(err, os.ErrNotExist) {
 		file, _ = securejoin.OpenInRoot(config.DataDir, filepath.Join(wwwRoot, "404.html"))
-		err = fmt.Errorf("not found: %s", err.(*os.PathError).Path)
 	}
 
 	// acquire read capability to the file being served (if possible)
@@ -249,6 +248,9 @@ func ServePages(w http.ResponseWriter, r *http.Request) {
 		err = fmt.Errorf("method %s not allowed", r.Method)
 	}
 	if err != nil {
+		if pathErr, ok := err.(*os.PathError); ok {
+			err = fmt.Errorf("not found: %s", pathErr.Path)
+		}
 		log.Println("pages err:", err)
 	}
 }