Refine invoice template editor interactions

frontend/src/lib/api.ts

@@ -2,6 +2,16 @@ import { AUTH_TOKEN_STORAGE_KEY } from "./storage";
 
 const API_ROOT = import.meta.env.VITE_API_URL ?? (import.meta.env.DEV ? "http://localhost:8090/api" : "/api");
 
+export class ApiError extends Error {
+  status: number;
+
+  constructor(message: string, status: number) {
+    super(message);
+    this.name = "ApiError";
+    this.status = status;
+  }
+}
+
 type ApiErrorPayload = {
   message?: string;
   error?: string;
@@ -44,7 +54,7 @@ function authHeaders(): Record<string, string> {
 
 async function handleResponse<T>(response: Response): Promise<T> {
   if (!response.ok) {
-    throw new Error(await readErrorMessage(response));
+    throw new ApiError(await readErrorMessage(response), response.status);
   }
   if (response.status === 204) {
     return undefined as T;