refactor: move project to frontend directory

frontend/src/data/api/ApiUtils.ts

@@ -0,0 +1,17 @@
+export class ApiError extends Error {
+  readonly statusCode: number;
+
+  constructor(statusCode: number, message?: string) {
+    super(message);
+    this.statusCode = statusCode;
+  }
+}
+
+export function handleJsonResponse<T>(res: Promise<Response>): Promise<T> {
+  return res.then(async e => {
+    if (e.status === 200) {
+      return await e.json();
+    }
+    throw new ApiError(e.status, 'Api error ' + e.status + ': ' + await e.text());
+  });
+}