feat(platform-web): surface backend api errors

vehicle-data-platform/apps/web/src/api/client.ts

@@ -28,15 +28,40 @@ export type RawFrameQuery = {
   offset?: number;
 };
 
+type ApiErrorEnvelope = {
+  error?: {
+    code?: string;
+    message?: string;
+    detail?: string;
+  };
+};
+
 async function request<T>(path: string, init?: RequestInit): Promise<T> {
   const response = await fetch(path, init);
   if (!response.ok) {
-    throw new Error(`request failed ${response.status}`);
+    throw new Error(await responseErrorMessage(response));
   }
   const envelope = (await response.json()) as ApiEnvelope<T>;
   return envelope.data;
 }
 
+async function responseErrorMessage(response: Response) {
+  try {
+    const envelope = (await response.json()) as ApiErrorEnvelope;
+    const message = envelope.error?.message?.trim();
+    const detail = envelope.error?.detail?.trim();
+    if (message && detail) {
+      return `${message}: ${detail}`;
+    }
+    if (message) {
+      return message;
+    }
+  } catch {
+    // Fall back to status when the server does not return the platform envelope.
+  }
+  return `request failed ${response.status}`;
+}
+
 export const api = {
   dashboardSummary: () => request<DashboardSummary>('/api/dashboard/summary'),
   vehicles: (params = new URLSearchParams()) => request<Page<VehicleRow>>(`/api/vehicles?${params.toString()}`),