feat: add api types

src/lib/api/types.ts

@@ -0,0 +1,24 @@
+class ApiError extends Error {
+	constructor(
+		readonly status: number,
+		readonly code: string,
+		message: string,
+	) {
+		super(message);
+		this.name = 'ApiError';
+	}
+}
+
+const extractMessage = (err: unknown): string => {
+	if (err instanceof ApiError) return err.message;
+	if (err instanceof Error) return err.message;
+	return 'An unexpected error occurred';
+};
+
+const handleResponse = async <T>(res: Response): Promise<T> => {
+	if (res.ok) return res.json() as Promise<T>;
+	const body = await res.json().catch(() => ({ code: 'UNKNOWN', message: res.statusText }));
+	throw new ApiError(res.status, body.code ?? 'UNKNOWN', body.message ?? res.statusText);
+};
+
+export { ApiError, extractMessage, handleResponse };