handle article not found when patching

backend/blog.go

@@ -293,7 +293,11 @@ func (h *ApiHandler) ServeBlogPatch(writer http.ResponseWriter, request *http.Re
 	article.Id = id
 	err = h.db.UpdateBlogArticle(article)
 	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			WriteError(writer, http.StatusNotFound, "article not found", nil)
+		} else {
 			WriteError(writer, http.StatusInternalServerError, "failed to write database", err)
+		}
 		return
 	}