A wrapper around the fetch function that validates the response body against a Zod schema

safeParse.ts

import z from "zod";

export async function safeFetch<T>(
  schema: z.Schema<T>,
  input: RequestInfo,
  init?: RequestInit
): Promise<T> {
  const response = await fetch(input, init);

  if (!response.ok) {
    throw newHTTPError("Unsuccessful response", response, init?.method);
  }

  const json = await response.json().catch(() => {
    throw newHTTPError("Not a JSON body", response, init?.method);
  });

  const result = schema.safeParse(json);
  if (!result.success) {
    throw newHTTPError("Unexpected response schema", response, init?.method);
  }

  return result.data;
}

async function newHTTPError(reason: string, response: Response, method?: string) {
  const text = await response.text().catch(() => null);
  const message = `Error fetching ${method} ${response.url} ${response.status}. ${reason}`;
  console.error(`${message}. Response body: ${text}`);
  return new HTTPError(response.status, message);
}

export class HTTPError extends Error {
  constructor(public status: number, message: string) {
    super(message);
    this.status = status;
  }
}

@jimniels right, updated! Thanks!